usb: dwc2: handle DMA buffer unmapping sanely

The driver's handling of DMA buffers for non-aligned transfers
was kind of nuts. For IN transfers, it left the URB DMA buffer
mapped until the transfer completed, then synced it, copied the
data from the bounce buffer, then synced it again.

Instead of that, just call usb_hcd_unmap_urb_for_dma() to unmap
the buffer before starting the transfer. Then no syncing is
required when doing the copy. This should also allow handling of
other types of mappings besides just dma_map_single() ones.

Also reduce the size of the bounce buffer allocation for Isoc
endpoints to 3K, since that's the largest possible transfer size.

Tested on Raspberry Pi and Altera SOCFPGA.

Signed-off-by: Paul Zimmerman <paulz@synopsys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 29 insertions, 13 deletions

diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index 4d918ed8d343..0a0e6f0ad15f 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -697,29 +697,45 @@ static void *dwc2_hc_init_xfer(struct dwc2_hsotg *hsotg,
 }
 
 static int dwc2_hc_setup_align_buf(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh,
-				   struct dwc2_host_chan *chan, void *bufptr)
+				   struct dwc2_host_chan *chan,
+				   struct dwc2_hcd_urb *urb, void *bufptr)
 {
 	u32 buf_size;
-
-	if (chan->ep_type != USB_ENDPOINT_XFER_ISOC)
-		buf_size = hsotg->core_params->max_transfer_size;
-	else
-		buf_size = 4096;
+	struct urb *usb_urb;
+	struct usb_hcd *hcd;
 
 	if (!qh->dw_align_buf) {
+		if (chan->ep_type != USB_ENDPOINT_XFER_ISOC)
+			buf_size = hsotg->core_params->max_transfer_size;
+		else
+			/* 3072 = 3 max-size Isoc packets */
+			buf_size = 3072;
+
 		qh->dw_align_buf = dma_alloc_coherent(hsotg->dev, buf_size,
 						      &qh->dw_align_buf_dma,
 						      GFP_ATOMIC);
 		if (!qh->dw_align_buf)
 			return -ENOMEM;
+		qh->dw_align_buf_size = buf_size;
 	}
 
-	if (!chan->ep_is_in && chan->xfer_len) {
-		dma_sync_single_for_cpu(hsotg->dev, chan->xfer_dma, buf_size,
-					DMA_TO_DEVICE);
-		memcpy(qh->dw_align_buf, bufptr, chan->xfer_len);
-		dma_sync_single_for_device(hsotg->dev, chan->xfer_dma, buf_size,
-					   DMA_TO_DEVICE);
+	if (chan->xfer_len) {
+		dev_vdbg(hsotg->dev, "%s(): non-aligned buffer\n", __func__);
+		usb_urb = urb->priv;
+
+		if (usb_urb) {
+			if (usb_urb->transfer_flags &
+			    (URB_SETUP_MAP_SINGLE | URB_DMA_MAP_SG |
+			     URB_DMA_MAP_PAGE | URB_DMA_MAP_SINGLE)) {
+				hcd = dwc2_hsotg_to_hcd(hsotg);
+				usb_hcd_unmap_urb_for_dma(hcd, usb_urb);
+			}
+			if (!chan->ep_is_in)
+				memcpy(qh->dw_align_buf, bufptr,
+				       chan->xfer_len);
+		} else {
+			dev_warn(hsotg->dev, "no URB in dwc2_urb\n");
+		}
 	}
 
 	chan->align_buf = qh->dw_align_buf_dma;
@@ -828,7 +844,7 @@ static int dwc2_assign_and_init_hc(struct dwc2_hsotg *hsotg, struct dwc2_qh *qh)
 	/* Non DWORD-aligned buffer case */
 	if (bufptr) {
 		dev_vdbg(hsotg->dev, "Non-aligned buffer\n");
-		if (dwc2_hc_setup_align_buf(hsotg, qh, chan, bufptr)) {
+		if (dwc2_hc_setup_align_buf(hsotg, qh, chan, urb, bufptr)) {
 			dev_err(hsotg->dev,
 				"%s: Failed to allocate memory to handle non-dword aligned buffer\n",
 				__func__);