[PATCH 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.sepp...@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;
 
-- 
2.13.6

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