usb: dwc3: gadget: handle request->zero

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@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 36f1cb7..2913068 100644 (file)
--- 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 e4203b7..9758018 100644 (file)
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1159,6 +1159,32 @@ 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)
 {
@@ -1172,6 +1198,16 @@ 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);
+
        spin_unlock_irqrestore(&dwc->lock, flags);
 
        return ret;
@@ -2744,6 +2780,12 @@ int dwc3_gadget_init(struct dwc3 *dwc)
                goto err3;
        }
 
+       dwc->zlp_buf = kzalloc(DWC3_ZLP_BUF_SIZE, GFP_KERNEL);
+       if (!dwc->zlp_buf) {
+               ret = -ENOMEM;
+               goto err4;
+       }
+
        dwc->gadget.ops                 = &dwc3_gadget_ops;
        dwc->gadget.speed               = USB_SPEED_UNKNOWN;
        dwc->gadget.sg_supported        = true;
@@ -2785,16 +2827,19 @@ int dwc3_gadget_init(struct dwc3 *dwc)
 
        ret = dwc3_gadget_init_endpoints(dwc);
        if (ret)
-               goto err4;
+               goto err5;
 
        ret = usb_add_gadget_udc(dwc->dev, &dwc->gadget);
        if (ret) {
                dev_err(dwc->dev, "failed to register udc\n");
-               goto err4;
+               goto err5;
        }
 
        return 0;
 
+err5:
+       kfree(dwc->zlp_buf);
+
 err4:
        dwc3_gadget_free_endpoints(dwc);
        dma_free_coherent(dwc->dev, DWC3_EP0_BOUNCE_SIZE,
@@ -2827,6 +2872,7 @@ void dwc3_gadget_exit(struct dwc3 *dwc)
                        dwc->ep0_bounce, dwc->ep0_bounce_addr);
 
        kfree(dwc->setup_buf);
+       kfree(dwc->zlp_buf);
 
        dma_free_coherent(dwc->dev, sizeof(*dwc->ep0_trb),
                        dwc->ep0_trb, dwc->ep0_trb_addr);