Only one of the two is really required, not both:
* have_rtscts or
* have_rtsgpio
In imx_rs485_config() this is done correctly, so RS485 is working,
just the error message is false.
Signed-off-by: Phil Eichinger <phil@zankapfel.net>
Reviewed-by: Fabio Estevam <fabio.estevam@nxp.com>
Fixes: b8f3bff057 ("serial: imx: Support common rs485 binding for RTS polarity"
Acked-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When the TTY buffers fill up to the configured maximum, a system lockup
occurs:
[ 598.820128] INFO: rcu_preempt detected stalls on CPUs/tasks:
[ 598.825796] 0-...!: (1 GPs behind) idle=5a6/2/0 softirq=1974/1974 fqs=1
[ 598.832577] (detected by 3, t=62517 jiffies, g=296, c=295, q=126)
[ 598.838755] Task dump for CPU 0:
[ 598.841977] swapper/0 R running task 0 0 0 0x00000022
[ 598.849023] Call trace:
[ 598.851476] __switch_to+0x98/0xb0
[ 598.854870] (null)
This can be prevented by doing a dummy read of the RX data register.
This issue affects both HSCIF and SCIF ports. Reported for R-Car H3 ES2.0;
reproduced and fixed on H3 ES1.1. Probably affects other R-Car platforms
as well.
Reported-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: stable <stable@vger.kernel.org>
Tested-by: Nguyen Viet Dung <dung.nguyen.aj@renesas.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add PCI ids for two variants of Brainboxes UC-260 quad port
PCI serial cards.
Suggested-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Nikola Ciprich <nikola.ciprich@linuxbox.cz>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
It will get the wrong virtual address because port->mapbase is not added
the correct reg-offset yet. We have to update it before earlycon_map()
is called
Signed-off-by: Greentime Hu <greentime@andestech.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: stable@vger.kernel.org
Fixes: 088da2a176 ("of: earlycon: Initialize port fields from DT properties")
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This is a followup on 44117a1d17 ("serial: core: mark port as
initialized after successful IRQ change").
Nikola has been using autoconfig via setserial and reported a crash
similar to what I fixed in the earlier mentioned commit. Here I do the
same fixup for the autoconfig. I wasn't sure that this is the right
approach. Nikola confirmed that it fixes his crash.
Fixes: b3b5764618 ("tty: serial_core: convert uart_open to use tty_port_open")
Link: http://lkml.kernel.org/r/20180131072000.GD1853@localhost.localdomain
Reported-by: Nikola Ciprich <nikola.ciprich@linuxbox.cz>
Tested-by: Nikola Ciprich <nikola.ciprich@linuxbox.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Tested-by: Nikola Ciprich <nikola.ciprich@linuxbox.cz>
Acked-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Do not fail on multiport cards in serial_pci_is_class_communication().
It restores behaviour for SUNIX multiport cards, that enumerated by
class and have a custom board data.
Moreover it allows users to reenumerate port-by-port from user space.
Fixes: 7d8905d064 ("serial: 8250_pci: Enable device after we check black list")
Reported-by: Nikola Ciprich <nikola.ciprich@linuxbox.cz>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Tested-by: Nikola Ciprich <nikola.ciprich@linuxbox.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
On our at91sam9260 based board the usart0 and usart1 ports report
their versions (ATMEL_US_VERSION) as 0x10302. This version is not
included in the current checks in the driver.
Signed-off-by: Jonas Danielsson <jonas@orbital-systems.com>
Acked-by: Richard Genoud <richard.genoud@gmail.com>
Acked-by: Nicolas Ferre <nicolas.ferre@microchip.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
A tty is hung up by __tty_hangup() setting file->f_op to
hung_up_tty_fops, which is skipped on ttys whose write operation isn't
tty_write(). This means that, for example, /dev/console whose write
op is redirected_tty_write() is never actually marked hung up.
Because n_tty_read() uses the hung up status to decide whether to
abort the waiting readers, the lack of hung-up marking can lead to the
following scenario.
1. A session contains two processes. The leader and its child. The
child ignores SIGHUP.
2. The leader exits and starts disassociating from the controlling
terminal (/dev/console).
3. __tty_hangup() skips setting f_op to hung_up_tty_fops.
4. SIGHUP is delivered and ignored.
5. tty_ldisc_hangup() is invoked. It wakes up the waits which should
clear the read lockers of tty->ldisc_sem.
6. The reader wakes up but because tty_hung_up_p() is false, it
doesn't abort and goes back to sleep while read-holding
tty->ldisc_sem.
7. The leader progresses to tty_ldisc_lock() in tty_ldisc_hangup()
and is now stuck in D sleep indefinitely waiting for
tty->ldisc_sem.
The following is Alan's explanation on why some ttys aren't hung up.
http://lkml.kernel.org/r/20171101170908.6ad08580@alans-desktop
1. It broke the serial consoles because they would hang up and close
down the hardware. With tty_port that *should* be fixable properly
for any cases remaining.
2. The console layer was (and still is) completely broken and doens't
refcount properly. So if you turn on console hangups it breaks (as
indeed does freeing consoles and half a dozen other things).
As neither can be fixed quickly, this patch works around the problem
by introducing a new flag, TTY_HUPPING, which is used solely to tell
n_tty_read() that hang-up is in progress for the console and the
readers should be aborted regardless of the hung-up status of the
device.
The following is a sample hung task warning caused by this issue.
INFO: task agetty:2662 blocked for more than 120 seconds.
Not tainted 4.11.3-dbg-tty-lockup-02478-gfd6c7ee-dirty #28
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
0 2662 1 0x00000086
Call Trace:
__schedule+0x267/0x890
schedule+0x36/0x80
schedule_timeout+0x23c/0x2e0
ldsem_down_write+0xce/0x1f6
tty_ldisc_lock+0x16/0x30
tty_ldisc_hangup+0xb3/0x1b0
__tty_hangup+0x300/0x410
disassociate_ctty+0x6c/0x290
do_exit+0x7ef/0xb00
do_group_exit+0x3f/0xa0
get_signal+0x1b3/0x5d0
do_signal+0x28/0x660
exit_to_usermode_loop+0x46/0x86
do_syscall_64+0x9c/0xb0
entry_SYSCALL64_slow_path+0x25/0x25
The following is the repro. Run "$PROG /dev/console". The parent
process hangs in D state.
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <signal.h>
#include <time.h>
#include <termios.h>
int main(int argc, char **argv)
{
struct sigaction sact = { .sa_handler = SIG_IGN };
struct timespec ts1s = { .tv_sec = 1 };
pid_t pid;
int fd;
if (argc < 2) {
fprintf(stderr, "test-hung-tty /dev/$TTY\n");
return 1;
}
/* fork a child to ensure that it isn't already the session leader */
pid = fork();
if (pid < 0) {
perror("fork");
return 1;
}
if (pid > 0) {
/* top parent, wait for everyone */
while (waitpid(-1, NULL, 0) >= 0)
;
if (errno != ECHILD)
perror("waitpid");
return 0;
}
/* new session, start a new session and set the controlling tty */
if (setsid() < 0) {
perror("setsid");
return 1;
}
fd = open(argv[1], O_RDWR);
if (fd < 0) {
perror("open");
return 1;
}
if (ioctl(fd, TIOCSCTTY, 1) < 0) {
perror("ioctl");
return 1;
}
/* fork a child, sleep a bit and exit */
pid = fork();
if (pid < 0) {
perror("fork");
return 1;
}
if (pid > 0) {
nanosleep(&ts1s, NULL);
printf("Session leader exiting\n");
exit(0);
}
/*
* The child ignores SIGHUP and keeps reading from the controlling
* tty. Because SIGHUP is ignored, the child doesn't get killed on
* parent exit and the bug in n_tty makes the read(2) block the
* parent's control terminal hangup attempt. The parent ends up in
* D sleep until the child is explicitly killed.
*/
sigaction(SIGHUP, &sact, NULL);
printf("Child reading tty\n");
while (1) {
char buf[1024];
if (read(fd, buf, sizeof(buf)) < 0) {
perror("read");
return 1;
}
}
return 0;
}
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Alan Cox <alan@llwyncelyn.cymru>
Cc: stable@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:
for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
done
with de-mangling cleanups yet to come.
NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do. But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.
The next patch from Al will sort out the final differences, and we
should be all done.
Scripted-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Update the ACPICA kernel code to upstream revision 20180105 including:
* Assorted fixes (Jung-uk Kim).
* Support for X32 ABI compilation (Anuj Mittal).
* Update of ACPICA copyrights to 2018 (Bob Moore).
- Prepare for future modifications to avoid executing the _STA control
method too early (Hans de Goede).
- Make the processor performance control library code ignore _PPC
notifications if they cannot be handled and fix up the C1 idle
state definition when it is used as a fallback state (Chen Yu,
Yazen Ghannam).
- Make it possible to use the SPCR table on x86 and to replace the
original IORT table with a new one from initrd (Prarit Bhargava,
Shunyong Yang).
- Add battery-related quirks for Asus UX360UA and UX410UAK and add
quirks for table parsing on Dell XPS 9570 and Precision M5530
(Kai Heng Feng).
- Address static checker warnings in the CPPC code (Gustavo Silva).
- Avoid printing a raw pointer to the kernel log in the smart
battery driver (Greg Kroah-Hartman).
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Merge tag 'acpi-part2-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm
Pull more ACPI updates from Rafael Wysocki:
"These are mostly fixes and cleanups, a few new quirks, a couple of
updates related to the handling of ACPI tables and ACPICA copyrights
refreshment.
Specifics:
- Update the ACPICA kernel code to upstream revision 20180105
including:
* Assorted fixes (Jung-uk Kim)
* Support for X32 ABI compilation (Anuj Mittal)
* Update of ACPICA copyrights to 2018 (Bob Moore)
- Prepare for future modifications to avoid executing the _STA
control method too early (Hans de Goede)
- Make the processor performance control library code ignore _PPC
notifications if they cannot be handled and fix up the C1 idle
state definition when it is used as a fallback state (Chen Yu,
Yazen Ghannam)
- Make it possible to use the SPCR table on x86 and to replace the
original IORT table with a new one from initrd (Prarit Bhargava,
Shunyong Yang)
- Add battery-related quirks for Asus UX360UA and UX410UAK and add
quirks for table parsing on Dell XPS 9570 and Precision M5530 (Kai
Heng Feng)
- Address static checker warnings in the CPPC code (Gustavo Silva)
- Avoid printing a raw pointer to the kernel log in the smart battery
driver (Greg Kroah-Hartman)"
* tag 'acpi-part2-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
ACPI: sbshc: remove raw pointer from printk() message
ACPI: SPCR: Make SPCR available to x86
ACPI / CPPC: Use 64-bit arithmetic instead of 32-bit
ACPI / tables: Add IORT to injectable table list
ACPI / bus: Parse tables as term_list for Dell XPS 9570 and Precision M5530
ACPICA: Update version to 20180105
ACPICA: All acpica: Update copyrights to 2018
ACPI / processor: Set default C1 idle state description
ACPI / battery: Add quirk for Asus UX360UA and UX410UAK
ACPI: processor_perflib: Do not send _PPC change notification if not ready
ACPI / scan: Use acpi_bus_get_status() to initialize ACPI_TYPE_DEVICE devs
ACPI / bus: Do not call _STA on battery devices with unmet dependencies
PCI: acpiphp_ibm: prepare for acpi_get_object_info() no longer returning status
ACPI: export acpi_bus_get_status_handle()
ACPICA: Add a missing pair of parentheses
ACPICA: Prefer ACPI_TO_POINTER() over ACPI_ADD_PTR()
ACPICA: Avoid NULL pointer arithmetic
ACPICA: Linux: add support for X32 ABI compilation
ACPI / video: Use true for boolean value
SPCR is currently only enabled or ARM64 and x86 can use SPCR to setup
an early console.
General fixes include updating Documentation & Kconfig (for x86),
updating comments, and changing parse_spcr() to acpi_parse_spcr(),
and earlycon_init_is_deferred to earlycon_acpi_spcr_enable to be
more descriptive.
On x86, many systems have a valid SPCR table but the table version is
not 2 so the table version check must be a warning.
On ARM64 when the kernel parameter earlycon is used both the early console
and console are enabled. On x86, only the earlycon should be enabled by
by default. Modify acpi_parse_spcr() to allow options for initializing
the early console and console separately.
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Mark Salter <msalter@redhat.com>
Tested-by: Mark Salter <msalter@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Here is the set of "big" driver core patches for 4.16-rc1.
The majority of the work here is in the firmware subsystem, with reworks
to try to attempt to make the code easier to handle in the long run, but
no functional change. There's also some tree-wide sysfs attribute
fixups with lots of acks from the various subsystem maintainers, as well
as a handful of other normal fixes and changes.
And finally, some license cleanups for the driver core and sysfs code.
All have been in linux-next for a while with no reported issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core updates from Greg KH:
"Here is the set of "big" driver core patches for 4.16-rc1.
The majority of the work here is in the firmware subsystem, with
reworks to try to attempt to make the code easier to handle in the
long run, but no functional change. There's also some tree-wide sysfs
attribute fixups with lots of acks from the various subsystem
maintainers, as well as a handful of other normal fixes and changes.
And finally, some license cleanups for the driver core and sysfs code.
All have been in linux-next for a while with no reported issues"
* tag 'driver-core-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (48 commits)
device property: Define type of PROPERTY_ENRTY_*() macros
device property: Reuse property_entry_free_data()
device property: Move property_entry_free_data() upper
firmware: Fix up docs referring to FIRMWARE_IN_KERNEL
firmware: Drop FIRMWARE_IN_KERNEL Kconfig option
USB: serial: keyspan: Drop firmware Kconfig options
sysfs: remove DEBUG defines
sysfs: use SPDX identifiers
drivers: base: add coredump driver ops
sysfs: add attribute specification for /sysfs/devices/.../coredump
test_firmware: fix missing unlock on error in config_num_requests_store()
test_firmware: make local symbol test_fw_config static
sysfs: turn WARN() into pr_warn()
firmware: Fix a typo in fallback-mechanisms.rst
treewide: Use DEVICE_ATTR_WO
treewide: Use DEVICE_ATTR_RO
treewide: Use DEVICE_ATTR_RW
sysfs.h: Use octal permissions
component: add debugfs support
bus: simple-pm-bus: convert bool SIMPLE_PM_BUS to tristate
...
Here is the big tty/serial driver update for 4.16-rc1.
The usual number of various serial driver fixes and updates to try to
get them to work with crazy hardware configurations (seriously, how many
different ways are hardware engineers going to come up with to hook up a
simple UART?)
There is also some serdev bugfixes and updates, as well as a smattering
of other small fixes in here.
All have been in the linux-next tree for a while, with no reported
issues.
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'tty-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty/staging driver updates from Greg KH:
"Here is the big tty/serial driver update for 4.16-rc1.
The usual number of various serial driver fixes and updates to try to
get them to work with crazy hardware configurations (seriously, how
many different ways are hardware engineers going to come up with to
hook up a simple UART?)
There is also some serdev bugfixes and updates, as well as a
smattering of other small fixes in here.
All have been in the linux-next tree for a while, with no reported
issues"
* tag 'tty-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (65 commits)
tty: serial: exar: Relocate sleep wake-up handling
tty: fix data race between tty_init_dev and flush of buf
serial: imx: fix endless loop during suspend
serial: core: mark port as initialized after successful IRQ change
serdev: only match serdev devices
serdev: do not generate modaliases for controllers
serial: mxs-auart: don't use GPIOF_* with gpiod_get_direction
serial: 8250_dw: Revert "Improve clock rate setting"
MAINTAINERS: Add myself as designated reviewer for 8250_dw
gpio: serial: max310x: Support open-drain configuration for GPIOs
serdev: Fix serdev_uevent failure on ACPI enumerated serdev-controllers
serial: 8250_ingenic: Parse earlycon options
serial: 8250_ingenic: Add support for the JZ4770 SoC
serial: core: Make uart_parse_options take const char* argument
serial: 8250_of: fix return code when probe function fails to get reset
serial: imx: Only wakeup via RTSDEN bit if the system has RTS/CTS
serial: 8250_uniphier: fix error return code in uniphier_uart_probe()
tty: n_gsm: Allow ADM response in addition to UA for control dlci
tty: omap-serial: Fix initial on-boot RTS GPIO level
tty: serial: jsm: Add one check against NULL pointer dereference
...
Pull networking updates from David Miller:
1) Significantly shrink the core networking routing structures. Result
of http://vger.kernel.org/~davem/seoul2017_netdev_keynote.pdf
2) Add netdevsim driver for testing various offloads, from Jakub
Kicinski.
3) Support cross-chip FDB operations in DSA, from Vivien Didelot.
4) Add a 2nd listener hash table for TCP, similar to what was done for
UDP. From Martin KaFai Lau.
5) Add eBPF based queue selection to tun, from Jason Wang.
6) Lockless qdisc support, from John Fastabend.
7) SCTP stream interleave support, from Xin Long.
8) Smoother TCP receive autotuning, from Eric Dumazet.
9) Lots of erspan tunneling enhancements, from William Tu.
10) Add true function call support to BPF, from Alexei Starovoitov.
11) Add explicit support for GRO HW offloading, from Michael Chan.
12) Support extack generation in more netlink subsystems. From Alexander
Aring, Quentin Monnet, and Jakub Kicinski.
13) Add 1000BaseX, flow control, and EEE support to mvneta driver. From
Russell King.
14) Add flow table abstraction to netfilter, from Pablo Neira Ayuso.
15) Many improvements and simplifications to the NFP driver bpf JIT,
from Jakub Kicinski.
16) Support for ipv6 non-equal cost multipath routing, from Ido
Schimmel.
17) Add resource abstration to devlink, from Arkadi Sharshevsky.
18) Packet scheduler classifier shared filter block support, from Jiri
Pirko.
19) Avoid locking in act_csum, from Davide Caratti.
20) devinet_ioctl() simplifications from Al viro.
21) More TCP bpf improvements from Lawrence Brakmo.
22) Add support for onlink ipv6 route flag, similar to ipv4, from David
Ahern.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1925 commits)
tls: Add support for encryption using async offload accelerator
ip6mr: fix stale iterator
net/sched: kconfig: Remove blank help texts
openvswitch: meter: Use 64-bit arithmetic instead of 32-bit
tcp_nv: fix potential integer overflow in tcpnv_acked
r8169: fix RTL8168EP take too long to complete driver initialization.
qmi_wwan: Add support for Quectel EP06
rtnetlink: enable IFLA_IF_NETNSID for RTM_NEWLINK
ipmr: Fix ptrdiff_t print formatting
ibmvnic: Wait for device response when changing MAC
qlcnic: fix deadlock bug
tcp: release sk_frag.page in tcp_disconnect
ipv4: Get the address of interface correctly.
net_sched: gen_estimator: fix lockdep splat
net: macb: Handle HRESP error
net/mlx5e: IPoIB, Fix copy-paste bug in flow steering refactoring
ipv6: addrconf: break critical section in addrconf_verify_rtnl()
ipv6: change route cache aging logic
i40e/i40evf: Update DESC_NEEDED value to reflect larger value
bnxt_en: cleanup DIM work on device shutdown
...
Pull poll annotations from Al Viro:
"This introduces a __bitwise type for POLL### bitmap, and propagates
the annotations through the tree. Most of that stuff is as simple as
'make ->poll() instances return __poll_t and do the same to local
variables used to hold the future return value'.
Some of the obvious brainos found in process are fixed (e.g. POLLIN
misspelled as POLL_IN). At that point the amount of sparse warnings is
low and most of them are for genuine bugs - e.g. ->poll() instance
deciding to return -EINVAL instead of a bitmap. I hadn't touched those
in this series - it's large enough as it is.
Another problem it has caught was eventpoll() ABI mess; select.c and
eventpoll.c assumed that corresponding POLL### and EPOLL### were
equal. That's true for some, but not all of them - EPOLL### are
arch-independent, but POLL### are not.
The last commit in this series separates userland POLL### values from
the (now arch-independent) kernel-side ones, converting between them
in the few places where they are copied to/from userland. AFAICS, this
is the least disruptive fix preserving poll(2) ABI and making epoll()
work on all architectures.
As it is, it's simply broken on sparc - try to give it EPOLLWRNORM and
it will trigger only on what would've triggered EPOLLWRBAND on other
architectures. EPOLLWRBAND and EPOLLRDHUP, OTOH, are never triggered
at all on sparc. With this patch they should work consistently on all
architectures"
* 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (37 commits)
make kernel-side POLL... arch-independent
eventpoll: no need to mask the result of epi_item_poll() again
eventpoll: constify struct epoll_event pointers
debugging printk in sg_poll() uses %x to print POLL... bitmap
annotate poll(2) guts
9p: untangle ->poll() mess
->si_band gets POLL... bitmap stored into a user-visible long field
ring_buffer_poll_wait() return value used as return value of ->poll()
the rest of drivers/*: annotate ->poll() instances
media: annotate ->poll() instances
fs: annotate ->poll() instances
ipc, kernel, mm: annotate ->poll() instances
net: annotate ->poll() instances
apparmor: annotate ->poll() instances
tomoyo: annotate ->poll() instances
sound: annotate ->poll() instances
acpi: annotate ->poll() instances
crypto: annotate ->poll() instances
block: annotate ->poll() instances
x86: annotate ->poll() instances
...
Exar sleep wake-up handling has been done on a per-channel basis by
virtue of INT0 being accessible from each channel's address space. I
believe this was initially done out of necessity, but now that Exar
devices have their own driver, we can do things more efficiently by
registering a dedicated INT0 handler at the PCI device level.
I see this change providing the following benefits:
1. If more than one port is active, eliminates the redundant bus
cycles for reading INT0 on every interrupt.
2. This note associated with hooking in the per-channel handler in
8250_port.c is resolved:
/* Fixme: probably not the best place for this */
Cc: Matt Schulte <matts@commtech-fastcom.com>
Signed-off-by: Aaron Sierra <asierra@xes-inc.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Adds serdev_device_set_parity() and an implementation for ttyport.
The interface uses an enum with the values SERIAL_PARITY_NONE,
SERIAL_PARITY_EVEN and SERIAL_PARITY_ODD.
Signed-off-by: Ulrich Hecht <ulrich.hecht+renesas@gmail.com>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Reviewed-by: Johan Hovold <johan@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
There can be a race, if receive_buf call comes before
tty initialization completes in n_tty_open and tty->disc_data
may be NULL.
CPU0 CPU1
---- ----
000|n_tty_receive_buf_common() n_tty_open()
-001|n_tty_receive_buf2() tty_ldisc_open.isra.3()
-002|tty_ldisc_receive_buf(inline) tty_ldisc_setup()
Using ldisc semaphore lock in tty_init_dev till disc_data
initializes completely.
Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Before we go into suspend mode, we enable the imx uart's interrupt for
the awake bit in the UART Status Register 1. If, for some reason, the
awake bit is already set before we enter suspend mode, we get an
interrupt immediately when we enable interrupts for awake. The uart's
clk_ipg is disabled at this point (unless there's an ongoing transfer).
We end up in the interrupt handler, which usually tries to clear the
awake bit. This doesn't work with the clock disabled. Therefore, we
keep getting interrupts forever, resulting in an endless loop.
Clear the awake bit before setting the awaken bit to signal that we want
an imx interrupt when the awake bit will be set. This ensures that we're
not woken up by events that happened before we started going into
suspend mode.
Change the clock handling so that suspend prepares and enables the clock
and suspend_noirq disables it. Revert these operations in resume_noirq and
resume.
With these preparations in place, we can now modify awake and awaken in
the suspend function when the actual imx interrupt is disabled and the
required clk_ipg is active.
Update the thaw and freeze functions to use the new clock handling since
we share the suspend_noirq function between suspend and hibernate.
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
setserial changes the IRQ via uart_set_info(). It invokes
uart_shutdown() which free the current used IRQ and clear
TTY_PORT_INITIALIZED. It will then update the IRQ number and invoke
uart_startup() before returning to the caller leaving
TTY_PORT_INITIALIZED cleared.
The next open will crash with
| list_add double add: new=ffffffff839fcc98, prev=ffffffff839fcc98, next=ffffffff839fcc98.
since the close from the IOCTL won't free the IRQ (and clean the list)
due to the TTY_PORT_INITIALIZED check in uart_shutdown().
There is same pattern in uart_do_autoconfig() and I *think* it also
needs to set TTY_PORT_INITIALIZED there.
Is there a reason why uart_startup() does not set the flag by itself
after the IRQ has been acquired (since it is cleared in uart_shutdown)?
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Only serdev devices (a.k.a. clients or slaves) are bound to drivers so
bail out early from match() in case the device is not a serdev device
(i.e. if it's a serdev controller).
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Serdev controllers are not bound to any drivers and it therefore makes
no sense to generate modaliases for them.
This has already been fixed separately for ACPI controllers for which
uevent errors were also being logged during probe due to the missing
ACPI companions (from which ACPI modaliases are generated).
This patch moves the modalias handling from the bus type to the client
device type. Specifically, this means that only serdev devices (a.k.a.
clients or slaves) will have have MODALIAS fields in their uevent
environments and corresponding modalias sysfs attributes.
Also add the missing static keyword for the modalias device attribute
when moving the definition.
Reported-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The documentation was wrong, gpiod_get_direction() returns 0/1 instead
of the GPIOF_* flags. The docs were fixed with commit 94fc73094a
("gpio: correct docs about return value of gpiod_get_direction"). Now,
fix this user (until a better, system-wide solution is in place). This
also means we can drop the deprecated use of 'linux/gpio.h'. Yay!
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The commit
de9e33bdfa ("serial: 8250_dw: Improve clock rate setting")
obviously tries to cure symptoms, and not a root cause.
The root cause is the non-flexible rate calculation inside the
corresponding clock driver. What we need is to provide maximum UART
divisor value to the clock driver to allow it do the job transparently
to the caller.
Since from the initial commit message I have got no clue which clock
driver actually needs to be amended, I leave this exercise to the people
who know better the case.
Moreover, it seems [1] the fix introduced a regression. And possible
even one more [2].
Taking above, revert the commit de9e33bdfa for now.
[1]: https://www.spinics.net/lists/linux-serial/msg28872.html
[2]: https://github.com/Dunedan/mbp-2016-linux/issues/29#issuecomment-357583782
Fixes: de9e33bdfa ("serial: 8250_dw: Improve clock rate setting")
Cc: stable <stable@vger.kernel.org> # 4.15
Cc: Ed Blake <ed.blake@sondrel.com>
Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Cc: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The push-pull vs. open-drain are the only supported output modes. The
inputs are always unconditionally equipped with weak pull-downs. That's
the only mode, so there's probably no point in exporting that. I wonder
if it's worthwhile to provide a custom dbg_show method to indicate the
current status of the outputs, though.
This patch and [1] for i2c-gpio together make it possible to bit-bang an
I2C bus over GPIOs of an UART which is connected via SPI :). Yes, this
is crazy, but it's fast enough (while on a 26Mhz SPI HW bus with a
dual-core 1.6GHz CPU) to drive an I2C bus at 200kHz, according to my
scope.
[1] https://patchwork.ozlabs.org/patch/852591/
Signed-off-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
ACPI enumerated serdev-controllers do not have an ACPI companion, the ACPI
companion belongs to the serdev-device child of the serdev-controller, not
to the controller itself. This was causing serdev_uevent to always return
-ENODEV when called on a serdev-controller leading to errors like these:
kernel: serial serial0: uevent: failed to send synthetic uevent
being logged. This commit modifies serdev_uevent to directly return 0
when called on an ACPI enumerated serdev-controller fixing this.
Note: I do not think that setting a modalias on a devicetree enumerated
serdev-controller makes sense either. So perhaps the !dev->of_node part of
the check can be dropped too, but I'm not entirely sure that doing this
on devicetree too is correct.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In the devicetree, it is possible to specify the baudrate, parity,
bits, flow of the early console, by passing a configuration string like
this:
aliases {
serial0 = &uart0;
};
chosen {
stdout-path = "serial0:57600n8";
};
This, for instance, will configure the early console for a baudrate of
57600 bps, no parity, and 8 bits per baud.
This patches implements parsing of this configuration string in the
8250_ingenic driver, which previously just ignored it.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The JZ4770 SoC's UART is no different from the other JZ SoCs, so this
commit simply adds the ingenic,jz4770-uart compatible string.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The pointed string is never modified from within uart_parse_options, so
it should be marked as const in the function prototype.
Signed-off-by: Paul Cercueil <paul@crapouillou.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The error pointer from devm_reset_control_get_optional_shared() is
not propagated.
One of the most common problem scenarios is it returns -EPROBE_DEFER
when the reset controller has not probed yet. In this case, the
probe of the reset consumer should be deferred.
Fixes: e2860e1f62 ("serial: 8250_of: Add reset support")
Cc: stable@vger.kernel.org # v4.13+
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The wakeup mechanism via RTSDEN bit relies on the system using the RTS/CTS
lines, so only allow such wakeup method when the system actually has
RTS/CTS support.
Fixes: bc85734b12 ("serial: imx: allow waking up on RTSD")
Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Reviewed-by: Martin Kaiser <martin@kaiser.cx>
Acked-by: Fugang Duan <fugang.duan@nxp.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fix to return a negative error code from the port register error
handling case instead of 0, as done elsewhere in this function.
Fixes: 39be40ce06 ("serial: 8250_uniphier: fix serial port index in private data")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Acked-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Some devices have the control dlci stay in ADM mode instead of the UA
mode. This can seen at least on droid 4 when trying to open the ts
27.010 mux port. Enabling n_gsm debug mode shows the control dlci
always respond with DM to SABM instead of UA:
# modprobe n_gsm debug=0xff
# ldattach -d GSM0710 /dev/ttyS0 &
gsmld_output: 00000000: f9 03 3f 01 1c f9
--> 0) C: SABM(P)
gsmld_receive: 00000000: f9 03 1f 01 36 f9
<-- 0) C: DM(P)
...
$ minicom -D /dev/gsmtty1
minicom: cannot open /dev/gsmtty1: No error information
$ strace minicom -D /dev/gsmtty1
...
open("/dev/gsmtty1", O_RDWR|O_NOCTTY|O_NONBLOCK|O_LARGEFILE) = -1 EL2HLT
Note that this is different issue from other n_gsm -EL2HLT issues such
as timeouts when the control dlci does not respond at all.
The ADM mode seems to be a quite common according to "RF Wireless World"
article "GSM Issue-UE sends SABM and gets a DM response instead of
UA response":
This issue is most commonly observed in GSM networks where in UE sends
SABM and expects network to send UA response but it ends up receiving
DM response from the network. SABM stands for Set asynchronous balanced
mode, UA stands for Unnumbered Acknowledge and DA stands for
Disconnected Mode.
An RLP entity can be in one of two modes:
- Asynchronous Balanced Mode (ABM)
- Asynchronous Disconnected Mode (ADM)
Currently Linux kernel closes the control dlci after several retries
in gsm_dlci_t1() on DM. This causes n_gsm /dev/gsmtty ports to produce
error code -EL2HLT when trying to open them as the closing of control
dlci has already set gsm->dead.
Let's fix the issue by allowing control dlci stay in ADM mode after the
retries so the /dev/gsmtty ports can be opened and used. It seems that
it might take several attempts to get any response from the control
dlci, so it's best to allow ADM mode only after the SABM retries are
done.
Note that for droid 4 additional patches are needed to mux the ttyS0
pins and to toggle RTS gpio_149 to wake up the mdm6600 modem are also
needed to use n_gsm. And the mdm6600 modem needs to be powered on.
Cc: linux-serial@vger.kernel.org
Cc: Alan Cox <alan@llwyncelyn.cymru>
Cc: Jiri Prchal <jiri.prchal@aksignal.cz>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Marcel Partap <mpartap@gmx.net>
Cc: Michael Scott <michael.scott@linaro.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Russ Gorby <russ.gorby@intel.com>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Sebastian Reichel <sre@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The rs485 flag "SER_RS485_RTS_AFTER_SEND" was wrongly read from the GPIO
flags. This caused the RTS pin to be high during boot.
Signed-off-by: Rafael Gago Castano <rgc@hms.se>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
All calls to neo_copy_data_from_uart_to_queue() are safeguarded
against NULL dereference of its parameter, except the one that
this patch changes.
That said, let's play safe and check for NULL in this case too.
Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
After inspection made by Markus using Coccinelle software, he
observed that we could possibly be triggering a NULL pointer
dereference in 2 functions [0].
After discussion in mailing list, it was observed in fact
we have two unnecessary checks for NULL pointer, and they
were leading to Coccinelle warn. So, instead of reworking
the code as proposed by him, we hereby remove the
unnecessary checks, and also some unneeded extra lines in
the code.
These two unnecessary NULL checks were tracked in the call
chain as never NULL, so they can be safely removed.
No functional changes are intended.
[0] https://lkml.org/lkml/2017/11/29/705
Suggested-by: Markus Elfring <elfring@users.sourceforge.net>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Add code implementing managed version of serdev_device_open() for
serdev device drivers that "open" the device during driver's lifecycle
only once (e.g. opened in .probe() and closed in .remove()).
Acked-by: Philippe Ombredanne <pombredanne@nexb.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Using devres infrastructure it is possible to write a serdev driver
that doesn't have any code that needs to be called as a part of
.remove. Add code to make .remove optional.
Acked-by: Philippe Ombredanne <pombredanne@nexb.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Rob Herring <robh@kernel.org>
Reviewed-by: Sebastian Reichel <sebastian.reichel@collabora.co.uk>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>
We added support for EXTPROC back in 2010 in commit 26df6d1340 ("tty:
Add EXTPROC support for LINEMODE") and the intent was to allow it to
override some (all?) ICANON behavior. Quoting from that original commit
message:
There is a new bit in the termios local flag word, EXTPROC.
When this bit is set, several aspects of the terminal driver
are disabled. Input line editing, character echo, and mapping
of signals are all disabled. This allows the telnetd to turn
off these functions when in linemode, but still keep track of
what state the user wants the terminal to be in.
but the problem turns out that "several aspects of the terminal driver
are disabled" is a bit ambiguous, and you can really confuse the n_tty
layer by setting EXTPROC and then causing some of the ICANON invariants
to no longer be maintained.
This fixes at least one such case (TIOCINQ) becoming unhappy because of
the confusion over whether ICANON really means ICANON when EXTPROC is set.
This basically makes TIOCINQ match the case of read: if EXTPROC is set,
we ignore ICANON. Also, make sure to reset the ICANON state ie EXTPROC
changes, not just if ICANON changes.
Fixes: 26df6d1340 ("tty: Add EXTPROC support for LINEMODE")
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Reported-by: syzkaller <syzkaller@googlegroups.com>
Cc: Jiri Slaby <jslaby@suse.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In case that CONFIG_SLUB_DEBUG is on and pty is used, races between
release_one_tty and flush_to_ldisc work threads may happen and lead
to use-after-free condition on tty->link->port. Because SLUB_DEBUG
is turned on, freed tty->link->port is filled with POISON_FREE value.
So far without SLUB_DEBUG, port was filled with zero and flush_to_ldisc
could return without a problem by checking if tty is NULL.
CPU 0 CPU 1
----- -----
release_tty pty_write
cancel_work_sync(tty) to = tty->link
tty_kref_put(tty->link) tty_schedule_flip(to->port)
<< workqueue >> ...
release_one_tty ...
pty_cleanup ...
kfree(tty->link->port) << workqueue >>
flush_to_ldisc
tty = READ_ONCE(port->itty)
tty is 0x6b6b6b6b6b6b6b6b
!!PANIC!! access tty->ldisc
Unable to handle kernel paging request at virtual address 6b6b6b6b6b6b6b93
pgd = ffffffc0eb1c3000
[6b6b6b6b6b6b6b93] *pgd=0000000000000000, *pud=0000000000000000
------------[ cut here ]------------
Kernel BUG at ffffff800851154c [verbose debug info unavailable]
Internal error: Oops - BUG: 96000004 [#1] PREEMPT SMP
CPU: 3 PID: 265 Comm: kworker/u8:9 Tainted: G W 3.18.31-g0a58eeb #1
Hardware name: Qualcomm Technologies, Inc. MSM 8996pro v1.1 + PMI8996 Carbide (DT)
Workqueue: events_unbound flush_to_ldisc
task: ffffffc0ed610ec0 ti: ffffffc0ed624000 task.ti: ffffffc0ed624000
PC is at ldsem_down_read_trylock+0x0/0x4c
LR is at tty_ldisc_ref+0x24/0x4c
pc : [<ffffff800851154c>] lr : [<ffffff800850f6c0>] pstate: 80400145
sp : ffffffc0ed627cd0
x29: ffffffc0ed627cd0 x28: 0000000000000000
x27: ffffff8009e05000 x26: ffffffc0d382cfa0
x25: 0000000000000000 x24: ffffff800a012f08
x23: 0000000000000000 x22: ffffffc0703fbc88
x21: 6b6b6b6b6b6b6b6b x20: 6b6b6b6b6b6b6b93
x19: 0000000000000000 x18: 0000000000000001
x17: 00e80000f80d6f53 x16: 0000000000000001
x15: 0000007f7d826fff x14: 00000000000000a0
x13: 0000000000000000 x12: 0000000000000109
x11: 0000000000000000 x10: 0000000000000000
x9 : ffffffc0ed624000 x8 : ffffffc0ed611580
x7 : 0000000000000000 x6 : ffffff800a42e000
x5 : 00000000000003fc x4 : 0000000003bd1201
x3 : 0000000000000001 x2 : 0000000000000001
x1 : ffffff800851004c x0 : 6b6b6b6b6b6b6b93
Signed-off-by: Sahara <keun-o.park@darkmatter.ae>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Prior to this patch, the code would happily trigger TX on some ports
before having a chance of reading the RX buffer from the rest of them.
When no flow control was used, this led to RX buffer overruns and
therefore lost data under certain circumstances.
I was able to reproduce this with MAX14830 (that's a quad channel one)
and a simple daisy-chain of RX and TX ports on the eval board:
- TX0 -> RX1
- TX1 -> RX2
- TX2 -> RX3
- TX3 -> RX0
I was testing this by transferring 2MB of data at 115200 baud via each
port. I used a Solidrun Clearfog Base (Armada 388) which was talking to
the UART over an SPI bus clocked at 26MHz (the chip's maximum). Without
this patch, I would always get a "Possible RX FIFO overrun" in dmesg,
and fewer-than-expected amount of bytes received over ttyMAX0. Results
on ttyMAX{1,2,3} tended to be correct all the time, even without the
previous patches in this series and with PIO SPI transfers ("indirect
mode" as the Marvell datasheet calls it), so I assume that heavy
congestion is needed in order to reproduce this.
A drawback of this patch is that the throughput gets reduced "a bit".
Previously, a 115200 baud resulted in about 11.2kBps throughput as
reported by a simple `pv`. With this patch, the throughput of four
parallel streams is roughly 7kBps each, and 9kBps for three streams.
There is no slowdown for one or two parallel streams.
Situation is worse if bytes are being read one-by-one (such as if the
userspace wants to perform parity/framing/break checking) and therefore
without the batched reads.
With just this patch and no other modifications on top of 4.14, I was
only getting roughly 3.6kBps with four parallel streams. The
single-stream performance was the same, and I was seeing about 7.2kBps
with two parallel streams. `perf top` said that a substantial amount of
time was spent in `finish_task_switch`, `_raw_spin_unlock_irqrestore`
and `__timer_delay`.
Signed-off-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The hardware has a 128 byte RX FIFO buffer for each independent UART.
Previously, the code was always reading that byte-by-byte via
independent SPI transactions and the associated overhead. In practice,
this led to up to eight bytes over SPI for just one byte in the UART's
RX FIFO:
- reading the global IRQ register (two bytes, one for command, the other
for data)
- reading one UART's ISR (again two bytes)
- reading the byte count (two bytes yet again)
- finally, reading one byte of the FIFO via another two-byte transaction
We cannot always use a batched read. If the TTY is set to intercept
break conditions or report framing or parity errors, then it is required
to check the Line Status Register (LSR) for each byte which is read from
the RX FIFO. The documentation does not show a way of doing that in a
single SPI transaction; registers 0x00 and 0x04 are separate.
In my testing, this is no silver bullet. I was feeding 2MB of random
data over four daisy-chaned UARTs of MAX14830, and this is the
distribution that I was getting:
- R <= 1: 7437322
- R <= 2: 162093
- R <= 4: 4093
- R <= 8: 4196
- R <= 16: 645
- R <= 32: 165
- R <= 64: 58
- R <= 128: 0
For a reference, batching the write operations works much better:
- W <= 1: 2664
- W <= 2: 1305
- W <= 4: 627
- W <= 8: 371
- W <= 16: 121
- W <= 32: 68
- W <= 64: 33
- W <= 128: 63139
That's probably because this HW/SW combination (Clearfog Base, Armada
388) is probably "good enough" to react to the chip's IRQ "fast enough"
most of the time. Still, I was getting RX overruns every now and then.
In future, I plan to improve this by letting the RX FIFO be filled a
little more (the chip has support for that and also for a "stale
timeout" to prevent additional starvation).
Signed-off-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
The transmit register supports batched writes. The key is simply to keep
sending additional bytes up to the FIFO size in the same SPI
transaction with the CS pin still being held low.
This duplicates the regmap infrastructure to a certain extent. There are
some provisions for multiple writes in there, but there does not appear
to be any support for those writes which are destined to the *same*
register (and also no standard for SPI bus transfers of these, anyway).
This patch does not solve every case (if the UART xmit circular buffer
wraps around, we're still doing two SPI transactions), but at least
it's not one-byte-per-transaction anymore.
This change does not touch the receive path at this time. Doing that in
the generic case appears to be impossible in the general case, because
the chips' status register contains data about the *current* byte in the
HW's Rx FIFO. We cannot read these two registers in one go,
unfortunately.
Signed-off-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
According to my chip's datasheet [1], the IRQ output is an open
collector pin which is suitable for sharing with other chips. The chip
also has a register which indicates which UART performed a change and
the driver checks that register already, so we have everything what is
needed to effectively share the IRQ GPIO.
[1] https://datasheets.maximintegrated.com/en/ds/MAX14830.pdf
Signed-off-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
As suggested by Russell King, a driver should not really care about bits
such as the interrupt polarity or whether it is edge- or level-
triggered. The reasons for that include:
- an upstream IRQ controller which cannot support edge- or
level-triggered interrupts,
- board design with a built-in inverter
The interrupt type is being already specified by the Device Tree,
anyway. Other drivers (gpio/gpio-tc3589x.c for example) already work in
this way, delegating the proper IRQ line setup to the DT and not
specifying anything by hand.
Also, there's no reason to have the IRQ flags split between two places.
The SPI probing is the only entry point anyway.
Signed-off-by: Jan Kundrát <jan.kundrat@cesnet.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Serdev does not use the file abstraction and specifically there will
never be anyone polling a file descriptor for POLLOUT events.
Just use plain wake_up_interruptible() in the write_wakeup callback and
document why it's there.
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
When compile-testing an allmodconfig kernel for a platform without
sh-sci serial ports, the SERIAL_SH_SCI_NR_UARTS symbol of type "int"
doesn't get assigned a numerical default value, but an empty string,
leading to a build failure:
.config:3814:warning: symbol value '' invalid for SERIAL_SH_SCI_NR_UARTS
...
make[3]: *** [silentoldconfig] Error 1
Fix this by explicitly providing a default value of 2, like before.
Reported-by: kbuild test robot <fengguang.wu@intel.com>
Fixes: f6731485a5 ("tty: serial: sh-sci: Hide number of ports config question")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
