On 12/3/2015 7:18 AM, Felipe Balbi wrote:
> So far, dwc3 has always missed request->zero
> handling for every endpoint. Let's implement
> that so we can handle cases where transfer must
> be finished with a ZLP.
>
> Note that dwc3 is a little special. Even though
> we're dealing with a ZLP, we still need a buffer
> of wMaxPacketSize bytes; to hide that detail from
> every gadget driver, we have a preallocated buffer
> of 1024 bytes (biggest bulk size) to use (and
> share) among all endpoints.
>
> Reported-by: Ravi B <ravibabu@xxxxxx>
> Signed-off-by: Felipe Balbi <balbi@xxxxxx>
> ---
>
> since v1:
> - remove unnecessary 'free_on_complete' flag
>
> since v2:
> - remove unnecessary 'out' label
>
> drivers/usb/dwc3/core.h | 3 +++
> drivers/usb/dwc3/gadget.c | 50 +++++++++++++++++++++++++++++++++++++++++++++--
> 2 files changed, 51 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> index 36f1cb74588c..29130682e547 100644
> --- a/drivers/usb/dwc3/core.h
> +++ b/drivers/usb/dwc3/core.h
> @@ -37,6 +37,7 @@
> #define DWC3_MSG_MAX 500
>
> /* Global constants */
> +#define DWC3_ZLP_BUF_SIZE 1024 /* size of a superspeed bulk */
> #define DWC3_EP0_BOUNCE_SIZE 512
> #define DWC3_ENDPOINTS_NUM 32
> #define DWC3_XHCI_RESOURCES_NUM 2
> @@ -647,6 +648,7 @@ struct dwc3_scratchpad_array {
> * @ctrl_req: usb control request which is used for ep0
> * @ep0_trb: trb which is used for the ctrl_req
> * @ep0_bounce: bounce buffer for ep0
> + * @zlp_buf: used when request->zero is set
> * @setup_buf: used while precessing STD USB requests
> * @ctrl_req_addr: dma address of ctrl_req
> * @ep0_trb: dma address of ep0_trb
> @@ -734,6 +736,7 @@ struct dwc3 {
> struct usb_ctrlrequest *ctrl_req;
> struct dwc3_trb *ep0_trb;
> void *ep0_bounce;
> + void *zlp_buf;
> void *scratchbuf;
> u8 *setup_buf;
> dma_addr_t ctrl_req_addr;
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index e341f034296f..e916c11ded59 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -1158,6 +1158,32 @@ out:
> return ret;
> }
>
> +static void __dwc3_gadget_ep_zlp_complete(struct usb_ep *ep,
> + struct usb_request *request)
> +{
> + dwc3_gadget_ep_free_request(ep, request);
> +}
> +
> +static int __dwc3_gadget_ep_queue_zlp(struct dwc3 *dwc, struct dwc3_ep *dep)
> +{
> + struct dwc3_request *req;
> + struct usb_request *request;
> + struct usb_ep *ep = &dep->endpoint;
> +
> + dwc3_trace(trace_dwc3_gadget, "queueing ZLP\n");
> + request = dwc3_gadget_ep_alloc_request(ep, GFP_ATOMIC);
> + if (!request)
> + return -ENOMEM;
> +
> + request->length = 0;
> + request->buf = dwc->zlp_buf;
> + request->complete = __dwc3_gadget_ep_zlp_complete;
> +
> + req = to_dwc3_request(request);
> +
> + return __dwc3_gadget_ep_queue(dep, req);
> +}
> +
> static int dwc3_gadget_ep_queue(struct usb_ep *ep, struct usb_request *request,
> gfp_t gfp_flags)
> {
> @@ -1171,6 +1197,16 @@ static int dwc3_gadget_ep_queue(struct usb_ep *ep, struct usb_request *request,
>
> spin_lock_irqsave(&dwc->lock, flags);
> ret = __dwc3_gadget_ep_queue(dep, req);
> +
> + /*
> + * Okay, here's the thing, if gadget driver has requested for a ZLP by
> + * setting request->zero, instead of doing magic, we will just queue an
> + * extra usb_request ourselves so that it gets handled the same way as
> + * any other request.
> + */
> + if (ret == 0 && request->zero && (request->length % ep->maxpacket == 0))
> + ret = __dwc3_gadget_ep_queue_zlp(dwc, dep);
Hi Felipe,
This causes regression with at least mass storage + Windows host.
When the gadget queues a ZLP, we end up sending two ZLPs which leads
to violating the MSC protocol.
The following fixes it:
- if (ret == 0 && request->zero && (request->length % ep->maxpacket == 0))
+ if (ret == 0 && request->zero && (request->length % ep->maxpacket == 0) &&
+ (request->length != 0))
Regards,
John
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