Hello. On 03/06/2015 06:14 PM, Mathias Nyman wrote:
From: Aleksander Morgado <aleksander@xxxxxxxxxxxxx>
When a control transfer has a short data stage, the xHCI controller generates two transfer events: a COMP_SHORT_TX event that specifies the untransferred amount, and a COMP_SUCCESS event. But when the data stage is not short, only the COMP_SUCCESS event occurs. Therefore, xhci-hcd must set urb->actual_length to urb->transfer_buffer_length while processing the COMP_SUCCESS event, unless urb->actual_length was set already by a previous COMP_SHORT_TX event.
The driver checks this by seeing whether urb->actual_length == 0, but this alone is the wrong test, as it is entirely possible for a short transfer to have an urb->actual_length = 0.
This patch changes the xhci driver to rely on a new td->urb_length_set flag, which is set to true when a COMP_SHORT_TX event is received and the URB length updated at that stage.
This fixes a bug which affected the HSO plugin, which relies on URBs with urb->actual_length == 0 to halt re-submitting the RX URB in the control endpoint.
Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Aleksander Morgado <aleksander@xxxxxxxxxxxxx> Signed-off-by: Mathias Nyman <mathias.nyman@xxxxxxxxxxxxxxx>
[...]
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h index 3b97f05..d066393 100644 --- a/drivers/usb/host/xhci.h +++ b/drivers/usb/host/xhci.h @@ -1,3 +1,4 @@ + /* * xHCI host controller driver *
Hm, I thought you've dropped this new line... WBR, Sergei -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html