openwrt/target/linux/generic/pending-4.14/171-usb-dwc2-Fix-inefficient-copy-of-unaligned-buffers.patch

From 81da1738eee68f1961e03bdeb2d60cf0eb4dd713 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Antti=20Sepp=C3=A4l=C3=A4?= <a.seppala@gmail.com>
Date: Thu, 5 Jul 2018 12:06:18 +0300
Subject: [PATCH 2/2] usb: dwc2: Fix inefficient copy of unaligned buffers
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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(-)

--- a/drivers/usb/dwc2/hcd.c
+++ b/drivers/usb/dwc2/hcd.c
@@ -2669,6 +2669,7 @@ static int dwc2_alloc_split_dma_aligned_
 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;
@@ -2679,9 +2680,14 @@ static void dwc2_free_dma_aligned_buffer
 			 dma_get_cache_alignment()),
 	       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;