tree ed09efd44e96b8d93b9ba9cb10d96f8462cfa79a
parent 4ce362711d78a4999011add3115b8f4b0bc25e8c
author Samuel Thibault <samuel.thibault@ens-lyon.org> 1489434608 +0100
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1489482451 +0800

usb-core: Add LINEAR_FRAME_INTR_BINTERVAL USB quirk

Some USB 2.0 devices erroneously report millisecond values in
bInterval. The generic config code manages to catch most of them,
but in some cases it's not completely enough.

The case at stake here is a USB 2.0 braille device, which wants to
announce 10ms and thus sets bInterval to 10, but with the USB 2.0
computation that yields to 64ms.  It happens that one can type fast
enough to reach this interval and get the device buffers overflown,
leading to problematic latencies.  The generic config code does not
catch this case because the 64ms is considered a sane enough value.

This change thus adds a USB_QUIRK_LINEAR_FRAME_INTR_BINTERVAL quirk
to mark devices which actually report milliseconds in bInterval,
and marks Vario Ultra devices as needing it.

Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>