USB: cdc-acm: add quirk for control-line state requests
authorJohan Hovold <johan@kernel.org>
Thu, 6 Nov 2014 17:08:33 +0000 (18:08 +0100)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 6 Nov 2014 20:25:40 +0000 (12:25 -0800)
commit2a8cdfde9237c4e1bd7c2e68c415b006491d23cc
treebad488692ec7149d3b326010b374f2419c80a139
parente5452dd4cb93b04b704eb6d4e7623178715f17ce
USB: cdc-acm: add quirk for control-line state requests

Add new quirk for devices that cannot handle control-line state
requests.

Note that we currently send these requests to all devices, regardless of
whether they claim to support it, but that errors are only logged if
support is claimed.

Since commit 0943d8ead30e ("USB: cdc-acm: use tty-port dtr_rts"), which
only changed the timings for these requests slightly, this has been
reported to cause occasional firmware crashes on Simtec Electronics
Entropy Key devices after re-enumeration. Enable the quirk for this
device.

Reported-by: Nix <nix@esperi.org.uk>
Tested-by: Nix <nix@esperi.org.uk>
Cc: stable <stable@vger.kernel.org> # v3.16
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/usb/class/cdc-acm.c
drivers/usb/class/cdc-acm.h