• Douglas Anderson's avatar
    usb: dwc2: host: Fix wMaxPacketSize handling (fix webcam regression) · babd1839
    Douglas Anderson authored
    In commit abb62184 ("usb: ch9: make usb_endpoint_maxp() return
    only packet size") the API to usb_endpoint_maxp() changed.  It used to
    just return wMaxPacketSize but after that commit it returned
    wMaxPacketSize with the high bits (the multiplier) masked off.  If you
    wanted to get the multiplier it was now up to your code to call the
    new usb_endpoint_maxp_mult() which was introduced in
    commit 541b6fe6 ("usb: add helper to extract bits 12:11 of
    wMaxPacketSize").
    
    Prior to the API change most host drivers were updated, but no update
    was made to dwc2.  Presumably it was assumed that dwc2 was too
    simplistic to use the multiplier and thus just didn't support a
    certain class of USB devices.  However, it turns out that dwc2 did use
    the multiplier and many devices using it were working quite nicely.
    That means that many USB devices have been broken since the API
    change.  One such device is a Logitech HD Pro Webcam C920.
    
    Specifically, though dwc2 didn't directly call usb_endpoint_maxp(), it
    did call usb_maxpacket() which in turn called usb_endpoint_maxp().
    
    Let's update dwc2 to work properly with the new API.
    
    Fixes: abb62184 ("usb: ch9: make usb_endpoint_maxp() return only packet size")
    Cc: stable@vger.kernel.org
    Acked-by: default avatarMinas Harutyunyan <hminas@synopsys.com>
    Reviewed-by: default avatarMatthias Kaehlcke <mka@chromium.org>
    Signed-off-by: default avatarDouglas Anderson <dianders@chromium.org>
    Signed-off-by: default avatarFelipe Balbi <felipe.balbi@linux.intel.com>
    babd1839
hcd.h 28.1 KB