usb: dwc3: gadget: align transfers to wMaxPacketSize

Instead of passing quirk_ep_out_aligned_size, we can use one extra TRB
to align transfer to wMaxPacketSize.
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/core.h

@@ -725,6 +725,7 @@ struct dwc3_hwparams {
  * @epnum: endpoint number to which this request refers
  * @trb: pointer to struct dwc3_trb
  * @trb_dma: DMA address of @trb
+ * @unaligned: true for OUT endpoints with length not divisible by maxp
  * @direction: IN or OUT direction flag
  * @mapped: true when request has been dma-mapped
  * @queued: true when request has been queued to HW
@@ -741,6 +742,7 @@ struct dwc3_request {
 	struct dwc3_trb		*trb;
 	dma_addr_t		trb_dma;
 
+	unsigned		unaligned:1;
 	unsigned		direction:1;
 	unsigned		mapped:1;
 	unsigned		started:1;

drivers/usb/dwc3/gadget.c

@@ -992,12 +992,33 @@ static void dwc3_prepare_one_trb_sg(struct dwc3_ep *dep,
 	int		i;
 
 	for_each_sg(sg, s, req->num_pending_sgs, i) {
+		unsigned int length = req->request.length;
+		unsigned int maxp = usb_endpoint_maxp(dep->endpoint.desc);
+		unsigned int rem = length % maxp;
 		unsigned chain = true;
 
 		if (sg_is_last(s))
 			chain = false;
 
+		if (rem && usb_endpoint_dir_out(dep->endpoint.desc) && !chain) {
+			struct dwc3	*dwc = dep->dwc;
+			struct dwc3_trb	*trb;
+
+			req->unaligned = true;
+
+			/* prepare normal TRB */
+			dwc3_prepare_one_trb(dep, req, true, i);
+
+			/* Now prepare one extra TRB to align transfer size */
+			trb = &dep->trb_pool[dep->trb_enqueue];
+			__dwc3_prepare_one_trb(dep, trb, dwc->bounce_addr,
+					maxp - rem, false, 0,
+					req->request.stream_id,
+					req->request.short_not_ok,
+					req->request.no_interrupt);
+		} else {
 			dwc3_prepare_one_trb(dep, req, chain, i);
+		}
 
 		if (!dwc3_calc_trbs_left(dep))
 			break;
@@ -1007,7 +1028,28 @@ static void dwc3_prepare_one_trb_sg(struct dwc3_ep *dep,
 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)) {
+		struct dwc3	*dwc = dep->dwc;
+		struct dwc3_trb	*trb;
+
+		req->unaligned = true;
+
+		/* prepare normal TRB */
+		dwc3_prepare_one_trb(dep, req, true, 0);
+
+		/* Now prepare one extra TRB to align transfer size */
+		trb = &dep->trb_pool[dep->trb_enqueue];
+		__dwc3_prepare_one_trb(dep, trb, dwc->bounce_addr, maxp - rem,
+				false, 0, req->request.stream_id,
+				req->request.short_not_ok,
+				req->request.no_interrupt);
+	} else {
 		dwc3_prepare_one_trb(dep, req, false, 0);
+	}
 }
 
 /*
@@ -2031,6 +2073,16 @@ static int __dwc3_cleanup_done_trbs(struct dwc3 *dwc, struct dwc3_ep *dep,
 	if (chain && (trb->ctrl & DWC3_TRB_CTRL_HWO))
 		trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
 
+	/*
+	 * If we're dealing with unaligned size OUT transfer, we will be left
+	 * with one TRB pending in the ring. We need to manually clear HWO bit
+	 * from that TRB.
+	 */
+	if (req->unaligned && (trb->ctrl & DWC3_TRB_CTRL_HWO)) {
+		trb->ctrl &= ~DWC3_TRB_CTRL_HWO;
+		return 1;
+	}
+
 	if ((trb->ctrl & DWC3_TRB_CTRL_HWO) && status != -ESHUTDOWN)
 		return 1;
 
@@ -2120,6 +2172,13 @@ static int dwc3_cleanup_done_reqs(struct dwc3 *dwc, struct dwc3_ep *dep,
 					event, status, chain);
 		}
 
+		if (req->unaligned) {
+			trb = &dep->trb_pool[dep->trb_dequeue];
+			ret = __dwc3_cleanup_done_trbs(dwc, dep, req, trb,
+					event, status, false);
+			req->unaligned = false;
+		}
+
 		req->request.actual = length - req->remaining;
 
 		if ((req->request.actual < length) && req->num_pending_sgs)
@@ -3058,12 +3117,6 @@ int dwc3_gadget_init(struct dwc3 *dwc)
 
 	dwc->gadget.max_speed		= dwc->maximum_speed;
 
-	/*
-	 * Per databook, DWC3 needs buffer size to be aligned to MaxPacketSize
-	 * on ep out.
-	 */
-	dwc->gadget.quirk_ep_out_aligned_size = true;
-
 	/*
 	 * REVISIT: Here we should clear all pending IRQs to be
 	 * sure we're starting from a well known location.