The receive FIFO wakeup latency estimate in the omap-serial driver is
three orders of magnitude too small. This effectively prevents the
MPU from going to a low-power state when CONFIG_CPU_IDLE=y. This is a
major power management regression and masks some other FIFO-related
bugs in the driver.
Fix by correcting the most egregious problem in the RX wakeup latency
estimate. There are several other flaws in the estimator; these will
be fixed by a separate patch series intended for 3.4.
The difference in low-power states with this patch can be observed via
debugfs in pm_debug/count.
This estimate does not have any effect when CONFIG_CPU_IDLE=n.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Alan Cox <alan@linux.intel.com>
Acked-by: Govindraj.R <govindraj.raja@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Prevent OMAP UARTs from going idle while they are still transferring
data in PIO mode. This works around an oversight in the OMAP UART
hardware present in OMAP34xx and earlier: an idle UART won't send a
wakeup when the TX FIFO threshold is reached. This causes long delays
during data transmission when the MPU powerdomain enters a low-power
mode. The MPU interrupt controller is not able to respond to
interrupts when it's in a low-power state, so the TX buffer is not
refilled until another wakeup event occurs.
This fix changes the erratum i291 DMA idle workaround. Rather than
toggling between force-idle and no-idle, it will toggle between
smart-idle and no-idle. The important part of the workaround is the
no-idle part, so this shouldn't result in any change in behavior.
This fix should work on all OMAP UARTs. Future patches intended for
the 3.4 merge window will make this workaround conditional on a
"feature" flag, and will use the OMAP36xx+ TX event wakeup support.
Thanks to Kevin Hilman <khilman@ti.com> for mentioning the erratum i291
workaround, which led to the development of this approach.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Acked-by: Govindraj.R <govindraj.raja@ti.com>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
In the (default) PIO mode, use a one-byte RX FIFO threshold. The OMAP
UART IP blocks do not appear to be capable of waking the system under
an RX timeout condition. Since the previous RX FIFO threshold was 16
bytes, this meant that omap-serial.c did not become aware of any
received data until all those bytes arrived or until another UART
interrupt occurred. This made the serial console and presumably other
serial applications (GPS, serial Bluetooth) unusable or extremely
slow. A 1-byte RX FIFO threshold also allows the MPU to enter a
low-power consumption state while waiting for the FIFO to fill.
This can be verified using the serial console by comparing the
behavior when "0123456789abcde" is pasted in from another window, with
the behavior when "0123456789abcdef" is pasted in. Since the former
string is less than sixteen bytes long, the string is not echoed for
some time, while the latter string is echoed immediately.
DMA operation is unaffected by this patch.
Thanks to Russell King - ARM Linux <linux@arm.linux.org.uk> for some
additional information on the standard behavior of the RX timeout
event, which was used to improve this commit description.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Govindraj Raja <govindraj.r@ti.com>
Cc: Alan Cox <alan@linux.intel.com>
Cc: Russell King <linux@arm.linux.org.uk>
Reviewed-by: Kevin Hilman <khilman@ti.com>
Tested-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This reverts commit 0a697b2225 as Paul
wants to rework it.
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Govindraj Raja <govindraj.r@ti.com>
Cc: Kevin Hilman <khilman@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
This reverts commit 43cf7c0beb as Paul
wants to redo it.
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Govindraj Raja <govindraj.r@ti.com>
Cc: Kevin Hilman <khilman@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
It seems that when the transmit FIFO threshold is reached on OMAP
UARTs, it does not result in a PRCM wakeup. This appears to be a
silicon bug. This means that if the MPU powerdomain is in a low-power
state, the MPU will not be awakened to refill the FIFO until the next
interrupt from another device.
The best solution, at least for the short term, would be for the OMAP
serial driver to call a OMAP subarchitecture function to prevent the
MPU powerdomain from entering a low power state while the FIFO has
data to transmit. However, we no longer have a clean way to do this,
since patches that add platform_data function pointers have been
deprecated by the OMAP maintainer. So we attempt to work around this
as well. The workarounds depend on the setting of CONFIG_CPU_IDLE.
When CONFIG_CPU_IDLE=n, the driver will now only transmit one byte at
a time. This causes the transmit FIFO threshold interrupt to stay
active until there is no more data to be sent. Thus, the MPU
powerdomain stays on during transmits. Aside from that energy
consumption penalty, each transmitted byte results in a huge number of
UART interrupts -- about five per byte. This wastes CPU time and is
quite inefficient, but is probably the most expedient workaround in
this case.
When CONFIG_CPU_IDLE=y, there is a slightly more direct workaround:
the PM QoS constraint can be abused to keep the MPU powerdomain on.
This results in a normal number of interrupts, but, similar to the
above workaround, wastes power by preventing the MPU from entering
WFI.
Future patches are planned for the 3.4 merge window to implement more
efficient, but also more disruptive, workarounds to these problems.
DMA operation is unaffected by this patch.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Govindraj Raja <govindraj.r@ti.com>
Cc: Kevin Hilman <khilman@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Ensure FIFO levels are set correctly in non-DMA mode (the default).
This patch will cause a receive FIFO threshold interrupt to be raised when
there is at least one byte in the RX FIFO. It will also cause a transmit
FIFO threshold interrupt when there is only one byte remaining in the TX
FIFO.
These changes fix the receive interrupt problem and part of the
transmit interrupt problem. A separate set of issues must be worked
around for the transmit path to have a basic level of functionality; a
subsequent patch will address these.
DMA operation is unaffected by this patch.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Govindraj Raja <govindraj.r@ti.com>
Cc: Kevin Hilman <khilman@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The function serial_omap_restore_context is called only from
serial_omap_runtime_resume which depends on CONFIG_PM_RUNTIME. Make
serial_omap_restore_context also compile conditionally.
if CONFIG_PM_RUNTIME is not defined below warn may be seen.
LD net/xfrm/built-in.o
drivers/tty/serial/omap-serial.c:1524: warning: 'serial_omap_restore_context' defined but not used
CC drivers/tty/vt/selection.o
Acked-by: Govindraj.R <govindraj.raja@ti.com>
Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The macro SET_SYSTEM_SLEEP_PM_OPS depends CONFIG_PM_SLEEP. The patch
defines the suspend and resume functions for CONFIG_PM_SLEEP instead of
CONFIG_SUSPEND.
Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
A significant part of the changes for these two platforms went into
power management, so they are split out into a separate branch.
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Merge tag 'pm' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc
power management changes for omap and imx
A significant part of the changes for these two platforms went into
power management, so they are split out into a separate branch.
* tag 'pm' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc: (65 commits)
ARM: imx6: remove __CPUINIT annotation from v7_invalidate_l1
ARM: imx6: fix v7_invalidate_l1 by adding I-Cache invalidation
ARM: imx6q: resume PL310 only when CACHE_L2X0 defined
ARM: imx6q: build pm code only when CONFIG_PM selected
ARM: mx5: use generic irq chip pm interface for pm functions on
ARM: omap: pass minimal SoC/board data for UART from dt
arm/dts: Add minimal device tree support for omap2420 and omap2430
omap-serial: Add minimal device tree support
omap-serial: Use default clock speed (48Mhz) if not specified
omap-serial: Get rid of all pdev->id usage
ARM: OMAP2+: hwmod: Add a new flag to handle hwmods left enabled at init
ARM: OMAP4: PRM: use PRCM interrupt handler
ARM: OMAP3: pm: use prcm chain handler
ARM: OMAP: hwmod: add support for selecting mpu_irq for each wakeup pad
ARM: OMAP2+: mux: add support for PAD wakeup interrupts
ARM: OMAP: PRCM: add suspend prepare / finish support
ARM: OMAP: PRCM: add support for chain interrupt handler
ARM: OMAP3/4: PRM: add functions to read pending IRQs, PRM barrier
ARM: OMAP2+: hwmod: Add API to enable IO ring wakeup
ARM: OMAP2+: mux: add wakeup-capable hwmod mux entries to dynamic list
...
Adapt the driver to device tree and pass minimal platform
data from device tree needed for console boot.
No power management features will be suppported for now
since it requires more tweaks around OCP settings
to toggle forceidle/noidle/smartidle bits and handling
remote wakeup and dynamic muxing.
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Reviewed-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Use a default clock speed of 48Mhz, instead of ending up with 0,
if platforms fail to specify a valid clock speed.
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Reviewed-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
With Device tree, pdev->id would no longer be Valid.
Hence get rid of all instances of its usage in the
driver. Device tree support for the driver is added
in subsequent patches.
Signed-off-by: Rajendra Nayak <rnayak@ti.com>
Reviewed-by: Rob Herring <rob.herring@calxeda.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Fixes below compilation warning.
drivers/tty/serial/omap-serial.c: In function 'serial_omap_irq':
drivers/tty/serial/omap-serial.c:228:29: warning: 'ch' may be used uninitialized in this function [-Wuninitialized]
Fix below sparse warning.
drivers/tty/serial/omap-serial.c:392:52: warning: incorrect type in argument 2 (different signedness)
drivers/tty/serial/omap-serial.c:392:52: expected int *status
drivers/tty/serial/omap-serial.c:392:52: got unsigned int *<noident>
Reported-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de> (for drivers/tty changes)
Signed-off-by: Kevin Hilman <khilman@ti.com>
Omap_uart_can_sleep function blocks system wide low power state until
uart is active remove this func and add qos requests to prevent
MPU from transitioning.
Keep qos request to default value which will allow MPU to transition
and while uart baud rate is available calculate the latency value
from the baudrate and use the same to hold constraint while uart clocks
are enabled, and if uart is auto-idled the constraint is updated with
default constraint value allowing MPU to transition.
Qos requests are blocking notifier calls so put these requests to
work queue, also the driver uses irq_safe version of runtime API's
and callbacks can be called in interrupt disabled context.
So to avoid warn on slow path warning while using qos update
API's from runtime callbacks use the qos_work_queue.
During bootup the runtime_resume call backs might not be called and runtime
callback gets called only after uart is idled by setting the autosuspend
timeout. So qos_request from runtime resume callback might not activated during
boot if uart baudrate is calculated during bootup for console uart, so schedule
the qos_work queue once we calc_latency while configuring the uart port.
Flush and complete any pending qos jobs in work queue while suspending.
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de> (for drivers/tty changes)
Signed-off-by: Kevin Hilman <khilman@ti.com>
When using DMA there are two timeouts defined. The first timeout,
rx_timeout, is really a polling rate in which software polls the
DMA status to see if the DMA has finished. This is necessary for
the RX side because we do not know how much data we will receive.
The secound timeout, RX_TIMEOUT, is a timeout after which the
DMA will be stopped if no more data is received. To make this
clearer, rename rx_timeout as rx_poll_rate and rename the
function serial_omap_rx_timeout() to serial_omap_rxdma_poll().
The OMAP-Serial driver defines an RX_TIMEOUT of 3 seconds that is
used to indicate when the DMA for UART can be stopped if no more
data is received. The value is a global definition that is applied
to all instances of the UART.
Each UART may be used for a different purpose and so the timeout
required may differ. Make this value configurable for each UART so
that this value can be optimised for power savings.
Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de> (for drivers/tty changes)
Signed-off-by: Kevin Hilman <khilman@ti.com>
The following UART parameters are defined within the UART driver:
1). Whether the UART uses DMA (dma_enabled), by default set to 0
2). The size of dma buffer (set to 4096 bytes)
3). The time after which the dma should stop if no more data is received.
4). The auto suspend delay that will be passed for pm_runtime_autosuspend
where uart will be disabled after timeout
Different UARTs may be used for different purpose such as the console,
for interfacing bluetooth chip, for interfacing to a modem chip, etc.
Therefore, it is necessary to be able to customize the above settings
for a given board on a per UART basis.
This change allows these parameters to be configured from the board file
and allows the parameters to be configured for each UART independently.
If a board does not define its own custom parameters for the UARTs, then
use the default parameters in the structure "omap_serial_default_info".
The default parameters are defined to be the same as the current settings
in the UART driver to avoid breaking the UART for any cuurnelty supported
boards. By default, make all boards use the default UART parameters.
Signed-off-by: Deepak K <deepak.k@ti.com>
Signed-off-by: Jon Hunter <jon-hunter@ti.com>
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de> (for drivers/tty changes)
Signed-off-by: Kevin Hilman <khilman@ti.com>
From the runtime callbacks enable hwmod wakeups for uart which will
internally enable io-pad wakeups for uarts if they have rx-pad pins
set as wakeup capabale.
Use the io-ring wakeup mechanism after uart clock gating and leave
the PM_WKST set for uart to default reset values cleanup the
code in serial.c which was handling PM_WKST reg.
Irq_chaing(PRM_DRIVER) is used to wakeup uart after uart clocks are gated
using pad wakeup mechanism.
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de> (for drivers/tty changes)
Signed-off-by: Kevin Hilman <khilman@ti.com>
Move the errata handling mechanism from serial.c to omap-serial file
and utilise the same func in driver file.
Errata i202, i291 are moved to be handled with omap-serial
Moving the errata macro from serial.c file to driver header file
as from on errata will be handled in driver file itself.
Corrected errata id from chapter reference 2.15 to errata id i291.
Removed errata and dma_enabled fields from omap_uart_state struct
as they are no more needed with errata handling done within omap-serial.
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Kevin Hilman <khilman@ti.com>
Avoid unconditional context restore every time we gate uart
clocks. Check whether context loss happened based on which
we can context restore uart regs from uart_port structure.
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de> (for drivers/tty changes)
Signed-off-by: Kevin Hilman <khilman@ti.com>
Remove the uart reset function which is configuring the
TX empty irq which can now be handled within omap-serial driver.
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de> (for drivers/tty changes)
Signed-off-by: Kevin Hilman <khilman@ti.com>
Add missing uart regs to uart_port structure which can be used in
context restore. Store dll, dlh, mdr1, scr, efr, lcr, mcr reg values
into uart_port structure while configuring individual port in termios
function.
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de> (for drivers/tty changes)
Signed-off-by: Kevin Hilman <khilman@ti.com>
Remove context save function from serial.c and move context restore
function to omap-serial. Remove all regs stored in omap_uart_state
for contex_save/restore, reg read write funcs used in context_save/restore,
io_addresses populated for read/write funcs.
Clock gating mechanism was done in serial.c and had no info on uart state
thus we needed context save and restore in serial.c
With runtime conversion and clock gating done within uart driver
context restore can be done from regs value available from uart_omap_port
structure.
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de> (for drivers/tty changes)
Signed-off-by: Kevin Hilman <khilman@ti.com>
Adapts omap-serial driver to use pm_runtime API's.
Use runtime runtime API's to handle uart clocks and obtain
device_usage statics. Set runtime API's usage to irq_safe so that
we can use get_sync from irq context. Auto-suspend for port specific
activities and put for reg access. Moving suspend/resume hooks
to dev_pm_ops structure and bind with config_suspend to avoid any
compilation warning if config_suspend is disabled.
By default uart autosuspend delay is set to -1 to avoid character loss
if uart's are autoidled and woken up on rx pin.
After boot up UART's can be autoidled by setting autosuspend delay from sysfs.
echo 3000 > /sys/devices/platform/omap/omap_uart.X/power/autosuspend_delay_ms
X=0,1,2,3 for UART1/2/3/4. Number of uarts available may vary across omap_soc.
Also if uart is not wakeup capable we can prevent runtime autosuspend by
forbiding runtime.
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Alan Cox <alan@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Kevin Hilman <khilman@ti.com>
The mapbase (start_address), membase(io_remap cookie) part of
pdata struct omap_uart_port_info are removed as this should be
derived within driver.
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de> (for drivers/tty changes)
Signed-off-by: Kevin Hilman <khilman@ti.com>
Currently we use a shared irq handler to identify uart activity and then
trigger a timer. By default the timeout value is zero and can be set or
modified from sysfs. If there was no uart activity for the period set
through sysfs, the timer will expire and call timer handler this will
set a flag can_sleep using which decision to gate uart clocks can be taken.
Since the clock gating mechanism is outside the uart driver, we currently
use this mechanism. In preparation to runtime implementation for omap-serial
driver we can cleanup this mechanism and use runtime API's to gate uart clocks.
Removes the following:
* timer related info from local uart_state struct
* the code used to set timeout value from sysfs.
* irqflags used to set shared irq handler.
* un-used function omap_uart_check_wakeup.
Signed-off-by: Govindraj.R <govindraj.raja@ti.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de> (for drivers/tty changes)
Signed-off-by: Kevin Hilman <khilman@ti.com>
The function check_modem_status returns an int currently it
is stored in a char.
Signed-off-by: Shubhrajyoti D <shubhrajyoti@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Fixes logic bug that software flow control cannot be disabled, because
serial_omap_configure_xonxoff() is not called if both IXON and IXOFF bits
are cleared.
Signed-off-by: Nick Pelly <npelly@google.com>
Acked-by: Govindraj.R <govindraj.raja@ti.com>
Tested-by: Govindraj.R <govindraj.raja@ti.com>
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Several fixes as well where the +1 was missing.
Done via coccinelle scripts like:
@@
struct resource *ptr;
@@
- ptr->end - ptr->start + 1
+ resource_size(ptr)
and some grep and typing.
Mostly uncompiled, no cross-compilers.
Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
OMAP can do also dynamic idling so wake-up enable register should be set
also while system is running. If UART_OMAP_WER is not set, then for instance
the RX activity cannot wake up the UART port that is sleeping.
This RX wake-up feature was working when the 8250 driver was used instead
of omap-serial. Reason for this is that the 8250 doesn't set the
UART_OMAP_WER and then arch/arm/mach-omap2/pm34xx.c ends up saving and
restoring the reset default which is the same than value
OMAP_UART_WER_MOD_WKUP here.
Fix this by moving the conditional UART_OMAP_WER write from serial_omap_pm
into serial_omap_startup where wake-up bits are set unconditionally.
Signed-off-by: Jarkko Nikula <jhnikula@gmail.com>
Cc: Govindraj.R <govindraj.raja@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Magic SysRq key is not working for OMAP on new serial
console ttyOx because SUPPORT_SYSRQ is not defined
for omap-serial.
This patch defines SUPPORT_SYSRQ in omap-serial and
enables handling of Magic SysRq character.
Further there is an issue of losing first break character.
Removing the reset of the lsr_break_flag fixes this issue.
Signed-off-by: Thomas Weber <weber@corscience.de>
Acked-by: Govindraj.R <govindraj.raja@ti.com>
Tested-by: Manjunath G Kondaiah <manjugk@ti.com>
Acked-by: Kevin Hilman <khilman@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
The serial drivers are really just tty drivers, so move them to
drivers/tty/ to make things a bit neater overall.
This is part of the tty/serial driver movement proceedure as proposed by
Arnd Bergmann and approved by everyone involved a number of months ago.
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Rogier Wolff <R.E.Wolff@bitwizard.nl>
Cc: Michael H. Warfield <mhw@wittsend.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
