Hi,
Tejas Joglekar <tejas.joglekar@xxxxxxxxxxxx> writes:
> For OUT endpoints, zero-length transfers require MaxPacketSize buffer as
> per the DWC_usb3 programming guide 3.30a section 4.2.3.3.
>
> This patch fixes this by explicitly checking zero length
> transfer to correctly pad up to MaxPacketSize.
>
> Signed-off-by: Tejas Joglekar <joglekar@xxxxxxxxxxxx>
do you have tracepoints of the problem?
> ---
> drivers/usb/dwc3/gadget.c | 5 +++--
> 1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index e2caf9e..f1089ec 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1069,7 +1069,8 @@ static void dwc3_prepare_one_trb_sg(struct dwc3_ep *dep,
> if (sg_is_last(s))
> chain = false;
>
> - if (rem && usb_endpoint_dir_out(dep->endpoint.desc) && !chain) {
> + if ((!length || rem) && usb_endpoint_dir_out(dep->endpoint.desc)
> + && !chain) {
are you 100% certain we have scatter/gather for a zlp? That doesn't make
sense to me.
> @@ -1114,7 +1115,7 @@ static void dwc3_prepare_one_trb_linear(struct dwc3_ep *dep,
> unsigned int maxp = usb_endpoint_maxp(dep->endpoint.desc);
> unsigned int rem = length % maxp;
>
> - if (rem && usb_endpoint_dir_out(dep->endpoint.desc)) {
> + if ((!length || rem) && usb_endpoint_dir_out(dep->endpoint.desc)) {
this is already taken care of:
> static void dwc3_prepare_one_trb_linear(struct dwc3_ep *dep,
> struct dwc3_request *req)
> {
> unsigned int length = req->request.length;
> unsigned int maxp = usb_endpoint_maxp(dep->endpoint.desc);
> unsigned int rem = length % maxp;
>
> if (rem && usb_endpoint_dir_out(dep->endpoint.desc)) {
[...]
> } else if (req->request.zero && req->request.length &&
> (IS_ALIGNED(req->request.length, maxp))) {
why isn't this branch triggering for you? Please capture and share
tracepoints exposing the problem
> struct dwc3 *dwc = dep->dwc;
> struct dwc3_trb *trb;
>
> req->needs_extra_trb = true;
>
> /* prepare normal TRB */
> dwc3_prepare_one_trb(dep, req, true, 0);
>
> /* Now prepare one extra TRB to handle ZLP */
> trb = &dep->trb_pool[dep->trb_enqueue];
> req->num_trbs++;
> __dwc3_prepare_one_trb(dep, trb, dwc->bounce_addr, 0,
> false, 1, req->request.stream_id,
> req->request.short_not_ok,
> req->request.no_interrupt);
> } else {
> dwc3_prepare_one_trb(dep, req, false, 0);
> }
> }
--
balbi
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