Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> writes:
> From: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
>
> When attaching an imx28 or imx53 in USB gadget mode to a Windows host and
> starting a rndis connection we see this message every 4-10 seconds:
>
> g_ether gadget: high speed config #2: RNDIS
>
> Analysis shows that each time this message is printed, the rndis connection is
> re-establish due to a reset because of a stalled endpoint (ep 0, dir 1). The
> endpoint is stalled because the reqeust complete bit on that endpoint is set,
> but in isr_tr_complete_low() the endpoint request list (mEp->qh.queue) is
> empty.
>
> This patch removed this check, because the code doesn't take the following
> situation into account:
>
> The loop over all endpoints in isr_tr_complete_handler() will call ep_nuke() on
> both ep0/dir0 and ep/dir1 in the first loop. Pending reqeusts will be flushed
> and completed here. There seems to be a race condition, the request is nuked,
> but the request complete bit will be set, too. The subsequent check (in
> ep0/dir1's loop cycle) for endpoint request list (mEp->qh.queue) empty will
> fail.
>
> Both other mainline chipidea drivers (mv_udc_core.c and fsl_udc_core.c) don't
> have this check.
>
> Signed-off-by: Michael Grzeschik <m.grzeschik@xxxxxxxxxxxxxx>
> Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx>
Makes sense to me,
Acked-by: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
> ---
> drivers/usb/chipidea/udc.c | 5 +----
> 1 file changed, 1 insertion(+), 4 deletions(-)
>
> diff --git a/drivers/usb/chipidea/udc.c b/drivers/usb/chipidea/udc.c
> index 2d8b609..d214448 100644
> --- a/drivers/usb/chipidea/udc.c
> +++ b/drivers/usb/chipidea/udc.c
> @@ -771,10 +771,7 @@ __acquires(mEp->lock)
> {
> struct ci13xxx_req *mReq, *mReqTemp;
> struct ci13xxx_ep *mEpTemp = mEp;
> - int uninitialized_var(retval);
> -
> - if (list_empty(&mEp->qh.queue))
> - return -EINVAL;
> + int retval = 0;
>
> list_for_each_entry_safe(mReq, mReqTemp, &mEp->qh.queue,
> queue) {
> --
> 1.7.10.4
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