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>
diff --git a/drivers/usb/class/cdc-acm.h b/drivers/usb/class/cdc-acm.h
index fc75651..d3251eb 100644
--- a/drivers/usb/class/cdc-acm.h
+++ b/drivers/usb/class/cdc-acm.h
@@ -121,6 +121,7 @@
unsigned int throttle_req:1; /* throttle requested */
u8 bInterval;
struct usb_anchor delayed; /* writes queued for a device about to be woken */
+ unsigned long quirks;
};
#define CDC_DATA_INTERFACE_TYPE 0x0a
@@ -132,3 +133,4 @@
#define NOT_A_MODEM BIT(3)
#define NO_DATA_INTERFACE BIT(4)
#define IGNORE_DEVICE BIT(5)
+#define QUIRK_CONTROL_LINE_STATE BIT(6)
