[2/2] usb: dwc2: Fix inefficient copy of unaligned buffers

[2/2] usb: dwc2: Fix inefficient copy of unaligned buffers

[Antti Seppälä]

Make sure only to copy any actual data rather than the whole buffer,
when releasing the temporary buffer used for unaligned non-isochronous
transfers.

Taken directly from commit 0efd937e27d5e ("USB: ehci-tegra: fix inefficient
copy of unaligned buffers")

Tested with Lantiq xRX200 (MIPS) and RPi Model B Rev 2 (ARM)

Signed-off-by: Antti Seppälä <a.seppala@gmail.com>
---
 drivers/usb/dwc2/hcd.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/usb/dwc2/hcd.c b/drivers/usb/dwc2/hcd.c
index 2ed0ac18e053..6e2cdd7b93d4 100644
--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -2668,6 +2668,7 @@ static int dwc2_alloc_split_dma_aligned_buf(struct dwc2_hsotg *hsotg,
 static void dwc2_free_dma_aligned_buffer(struct urb *urb)
 {
 	void *stored_xfer_buffer;
+	size_t length;
 
 	if (!(urb->transfer_flags & URB_ALIGNED_TEMP_BUFFER))
 		return;
@@ -2676,9 +2677,14 @@ static void dwc2_free_dma_aligned_buffer(struct urb *urb)
 	memcpy(&stored_xfer_buffer, urb->transfer_buffer +
 	       urb->transfer_buffer_length, sizeof(urb->transfer_buffer));
 
-	if (usb_urb_dir_in(urb))
-		memcpy(stored_xfer_buffer, urb->transfer_buffer,
-		       urb->transfer_buffer_length);
+	if (usb_urb_dir_in(urb)) {
+		if (usb_pipeisoc(urb->pipe))
+			length = urb->transfer_buffer_length;
+		else
+			length = urb->actual_length;
+
+		memcpy(stored_xfer_buffer, urb->transfer_buffer, length);
+	}
 	kfree(urb->transfer_buffer);
 	urb->transfer_buffer = stored_xfer_buffer;
 

[2/2] usb: dwc2: Fix inefficient copy of unaligned buffers

[Doug Anderson]

Hi,

On Thu, Jul 5, 2018 at 7:31 AM, Antti Seppälä <a.seppala@gmail.com> wrote:
> Make sure only to copy any actual data rather than the whole buffer,
> when releasing the temporary buffer used for unaligned non-isochronous
> transfers.
>
> Taken directly from commit 0efd937e27d5e ("USB: ehci-tegra: fix inefficient
> copy of unaligned buffers")
>
> Tested with Lantiq xRX200 (MIPS) and RPi Model B Rev 2 (ARM)
>
> Signed-off-by: Antti Seppälä <a.seppala@gmail.com>
> ---
>  drivers/usb/dwc2/hcd.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)

I haven't personally gone down and tracked down the validity of
"actual_length", but I agree that this matches what tegra has done and
seems sane.

Reviewed-by: Douglas Anderson <dianders@chromium.org>
---
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