linux.git/drivers/usb/class, branch v5.3-rc2

docs: usb: rename files to .rst and add them to drivers-api

2019-06-20T12:28:36+00:00

While there are a mix of things here, most of the stuff
were written from Kernel developer's PoV. So, add them to
the driver-api book.

A follow up for this patch would be to move documents from
there that are specific to sysadmins, adding them to the
admin-guide.

Signed-off-by: Mauro Carvalho Chehab 
Acked-by: Johan Hovold 
Acked-by: Felipe Balbi 
Signed-off-by: Greg Kroah-Hartman

usb: cdc-wdm: remove redundant assignment to rv

2019-06-03T13:21:56+00:00

The variable rv is assigned with a value that is never read and
it is re-assigned a new value on the next statement. The
assignment is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King 
Signed-off-by: Greg Kroah-Hartman

USB: cdc-acm: clean up throttle handling

2019-04-29T14:14:41+00:00

Clean up the throttle implementation by dropping the redundant
throttle_req flag which was a remnant from back when USB serial had only
a single read URB, something which was later carried over to cdc-acm.

Also convert the throttled flag to an atomic bit flag.

Signed-off-by: Johan Hovold 
Acked-by: Oliver Neukum 
Signed-off-by: Greg Kroah-Hartman

USB: cdc-acm: fix unthrottle races

2019-04-29T14:14:41+00:00

Fix two long-standing bugs which could potentially lead to memory
corruption or leave the port throttled until it is reopened (on weakly
ordered systems), respectively, when read-URB completion races with
unthrottle().

First, the URB must not be marked as free before processing is complete
to prevent it from being submitted by unthrottle() on another CPU.

	CPU 1				CPU 2
	================		================
	complete()			unthrottle()
	  process_urb();
	  smp_mb__before_atomic();
	  set_bit(i, free);		  if (test_and_clear_bit(i, free))
						  submit_urb();

Second, the URB must be marked as free before checking the throttled
flag to prevent unthrottle() on another CPU from failing to observe that
the URB needs to be submitted if complete() sees that the throttled flag
is set.

	CPU 1				CPU 2
	================		================
	complete()			unthrottle()
	  set_bit(i, free);		  throttled = 0;
	  smp_mb__after_atomic();	  smp_mb();
	  if (throttled)		  if (test_and_clear_bit(i, free))
		  return;			  submit_urb();

Note that test_and_clear_bit() only implies barriers when the test is
successful. To handle the case where the URB is still in use an explicit
barrier needs to be added to unthrottle() for the second race condition.

Also note that the first race was fixed by 36e59e0d70d6 ("cdc-acm: fix
race between callback and unthrottle") back in 2015, but the bug was
reintroduced a year later.

Fixes: 1aba579f3cf5 ("cdc-acm: handle read pipe errors")
Fixes: 088c64f81284 ("USB: cdc-acm: re-write read processing")
Signed-off-by: Johan Hovold 
Acked-by: Oliver Neukum 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

usb: cdc-acm: fix race during wakeup blocking TX traffic

2019-03-27T15:08:49+00:00

When the kernel is compiled with preemption enabled, the URB completion
handler can run in parallel with the work responsible for waking up the
tty layer. If the URB handler sets the EVENT_TTY_WAKEUP bit during the
call to tty_port_tty_wakeup() to signal that there is room for additional
input, it will be cleared at the end of this call. As a result, TX traffic
on the upper layer will be blocked.

This can be seen with a kernel configured with CONFIG_PREEMPT, and a fast
modem connected with PPP running over a USB CDC-ACM port.

Use test_and_clear_bit() instead, which ensures that each wakeup requested
by the URB completion code will trigger a call to tty_port_tty_wakeup().

Fixes: 1aba579f3cf5 cdc-acm: handle read pipe errors
Signed-off-by: Romain Izard 
Cc: stable 
Acked-by: Oliver Neukum 
Signed-off-by: Greg Kroah-Hartman

cdc-wdm: pass return value of recover_from_urb_loss

2019-02-19T13:41:38+00:00

'rv' is the correct return value, pass it upstream instead of 0

Fixes: 17d80d562fd7 ("USB: autosuspend for cdc-wdm")
Signed-off-by: YueHaibing 
Signed-off-by: Greg Kroah-Hartman

USB: add missing SPDX lines to Kconfig and Makefiles

2019-01-22T08:08:17+00:00

There are a few remaining drivers/usb/ files that do not have SPDX
identifiers in them, all of these are either Kconfig or Makefiles.  Add
the correct GPL-2.0 identifier to them to make scanning tools happy.

Signed-off-by: Greg Kroah-Hartman

usb: cdc-acm: send ZLP for Telit 3G Intel based modems

2019-01-07T16:23:29+00:00

Telit 3G Intel based modems require zero packet to be sent if
out data size is equal to the endpoint max packet size.

Signed-off-by: Daniele Palmas 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman

cdc-acm: fix abnormal DATA RX issue for Mediatek Preloader.

2018-12-20T15:38:52+00:00

Mediatek Preloader is a proprietary embedded boot loader for loading
Little Kernel and Linux into device DRAM.

This boot loader also handle firmware update. Mediatek Preloader will be
enumerated as a virtual COM port when the device is connected to Windows
or Linux OS via CDC-ACM class driver. When the USB enumeration has been
done, Mediatek Preloader will send out handshake command "READY" to PC
actively instead of waiting command from the download tool.

Since Linux 4.12, the commit "tty: reset termios state on device
registration" (93857edd9829e144acb6c7e72d593f6e01aead66) causes Mediatek
Preloader receiving some abnoraml command like "READYXX" as it sent.
This will be recognized as an incorrect response. The behavior change
also causes the download handshake fail. This change only affects
subsequent connects if the reconnected device happens to get the same minor
number.

By disabling the ECHO termios flag could avoid this problem. However, it
cannot be done by user space configuration when download tool open
/dev/ttyACM0. This is because the device running Mediatek Preloader will
send handshake command "READY" immediately once the CDC-ACM driver is
ready.

This patch wants to fix above problem by introducing "DISABLE_ECHO"
property in driver_info. When Mediatek Preloader is connected, the
CDC-ACM driver could disable ECHO flag in termios to avoid the problem.

Signed-off-by: Macpaul Lin 
Cc: stable@vger.kernel.org
Reviewed-by: Johan Hovold 
Acked-by: Oliver Neukum 
Signed-off-by: Greg Kroah-Hartman

usb: cdc-acm: add entry for Hiro (Conexant) modem

2018-11-20T11:12:06+00:00

The cdc-acm kernel module currently does not support the Hiro (Conexant)
H05228 USB modem. The patch below adds the device specific information:
	idVendor	0x0572
	idProduct	0x1349

Signed-off-by: Maarten Jacobs 
Acked-by: Oliver Neukum 
Cc: stable 
Signed-off-by: Greg Kroah-Hartman