linux/drivers/usb
Sebastian Andrzej Siewior 0f901c9801 usb: musb: dsps: redo the otg timer
According to the comments, we rely on the OTG timer because the core
does not expose some important OTG details. So far this is all I
know. After playing with OTG I stumbled over a problem:
musb is recognized as a B-device without a problem. Whenever a cable is
plugged, the VBUS rises, musb recognizes this as a starting session,
sets the MUSB_DEVCTL_SESSION bit by itself and a RESET interrupt occurs,
the session starts. Good.
After a disconnect, the timer is started and re-starts itself because
it remains in B_IDLE with the BDEVICE set. I didn't figure the the
reason or the need for it. Nothing changes here except for OTG state
from B to A device if the BDEVICE bit disappears. This doesn't make much
sense to me because nothing happens after this. _IF_ we receive an
interrupt before the state change then we may act on wrong condition.
Plugging a B-device (and letting MUSB act as host) doesn't work here.
The reason seems to be that the MUSB tries to start a session, it fails
and then it removes the bit. So we never start as a host.

This patch sets the MUSB_DEVCTL_SESSION bit in the IDLE state so musb
can try to establish a session as host. After the bit is set, musb tries
to start a session and if it fails it clears the bit. Therefore it will
try over and over again until a session either as host or as device is
established.

The readout of the MUSB_DEVCTL register after the removal the
MUSB_DEVCTL_SESSION (in A_WAIT_BCON) has been removed because it did not
contain the BDEVICE bit set (in the second read) leading to A_IDLE. After
plugging a host musb assumed that it is also a host and complained about
a missing reset. However a third read of the register has has the BDEVICE
bit set so it seems that it is not stable.
This mostly what da8xx.c is doing except that we set the timer also
after A_WAIT_BCON so the session bit can be triggered.

Whit this change I was able to keep am335x-evm in OTG mode and plug in
either a HOST or a DEVICE and in a random order and the device was
recognized.

Cc: stable@vger.kernel.org # v3.11
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>
2013-10-17 09:55:08 -05:00
..
atm usb: atm: speedtch: be careful with bInterval 2013-07-25 11:49:30 -07:00
c67x00 USB: c67x00: use dev_get_platdata() 2013-07-31 17:28:44 -07:00
chipidea usb: chipidea: USB_CHIPIDEA should depend on HAS_DMA 2013-09-25 17:30:39 -07:00
class USB: usbtmc: fix up attribute permissions 2013-08-25 15:12:03 -07:00
core usb/core/devio.c: Don't reject control message to endpoint with wrong direction bit 2013-09-25 17:30:39 -07:00
dwc3 usb: dwc3: core: use pm_runtime_put_sync() on remove 2013-10-11 08:34:28 -05:00
early fix build of EHCI debug port code when USB_CHIPIDEA but !USB_EHCI_HCD 2012-11-02 10:13:33 -07:00
gadget usb: gadget: s3c-hsotg: fix can_write limit for non-periodic endpoints 2013-10-15 08:46:51 -05:00
host USB: fsl/ehci: fix failure of checking PHY_CLK_VALID during reinitialization 2013-09-26 16:22:29 -07:00
image USB: regroup all depends on USB within an if USB block 2013-04-09 16:49:07 -07:00
misc usb: usbtest: bmAttributes would better be masked 2013-10-01 09:39:07 -05:00
mon USB: regroup all depends on USB within an if USB block 2013-04-09 16:49:07 -07:00
musb usb: musb: dsps: redo the otg timer 2013-10-17 09:55:08 -05:00
phy usb: phy: don't return with NULL from devm_usb_get_phy() 2013-10-11 13:50:38 -05:00
renesas_usbhs Remove GENERIC_HARDIRQ config option 2013-09-13 15:09:52 +02:00
serial USB: pl2303: distinguish between original and cloned HX chips 2013-09-17 09:36:10 -07:00
storage USB storage: audit sysfs attribute permissions 2013-08-27 13:13:07 -07:00
wusbcore Merge 3.11-rc6 into usb-next 2013-08-18 20:33:01 -07:00
Kconfig usb: Move definition of USB_EHCI_BIG_ENDIAN_MMIO et al. out side of the ifs. 2013-08-12 12:18:38 -07:00
Makefile usb: patches for v3.12 merge window 2013-08-13 15:28:01 -07:00
README
usb-common.c usb: common: introduce of_usb_get_maximum_speed() 2013-07-29 13:56:46 +03:00
usb-skeleton.c USB: usb-skeleton.c: add retry for nonblocking read 2013-07-25 12:01:13 -07:00

To understand all the Linux-USB framework, you'll use these resources:

    * This source code.  This is necessarily an evolving work, and
      includes kerneldoc that should help you get a current overview.
      ("make pdfdocs", and then look at "usb.pdf" for host side and
      "gadget.pdf" for peripheral side.)  Also, Documentation/usb has
      more information.

    * The USB 2.0 specification (from www.usb.org), with supplements
      such as those for USB OTG and the various device classes.
      The USB specification has a good overview chapter, and USB
      peripherals conform to the widely known "Chapter 9".

    * Chip specifications for USB controllers.  Examples include
      host controllers (on PCs, servers, and more); peripheral
      controllers (in devices with Linux firmware, like printers or
      cell phones); and hard-wired peripherals like Ethernet adapters.

    * Specifications for other protocols implemented by USB peripheral
      functions.  Some are vendor-specific; others are vendor-neutral
      but just standardized outside of the www.usb.org team.

Here is a list of what each subdirectory here is, and what is contained in
them.

core/		- This is for the core USB host code, including the
		  usbfs files and the hub class driver ("khubd").

host/		- This is for USB host controller drivers.  This
		  includes UHCI, OHCI, EHCI, and others that might
		  be used with more specialized "embedded" systems.

gadget/		- This is for USB peripheral controller drivers and
		  the various gadget drivers which talk to them.


Individual USB driver directories.  A new driver should be added to the
first subdirectory in the list below that it fits into.

image/		- This is for still image drivers, like scanners or
		  digital cameras.
../input/	- This is for any driver that uses the input subsystem,
		  like keyboard, mice, touchscreens, tablets, etc.
../media/	- This is for multimedia drivers, like video cameras,
		  radios, and any other drivers that talk to the v4l
		  subsystem.
../net/		- This is for network drivers.
serial/		- This is for USB to serial drivers.
storage/	- This is for USB mass-storage drivers.
class/		- This is for all USB device drivers that do not fit
		  into any of the above categories, and work for a range
		  of USB Class specified devices. 
misc/		- This is for all USB device drivers that do not fit
		  into any of the above categories.