[U-Boot] [PATH V3] usb: dwc2: invalidate the dcache before starting the DMA

[Eddie Cai]

We should invalidate the dcache before starting the DMA. In case there are
any dirty lines from the DMA buffer in the cache, subsequent cache-line
replacements may corrupt the buffer in memory while the DMA is still going on.
Cache-line replacement can happen if the CPU tries to bring some other memory
locations into the cache while the DMA is going on.

Signed-off-by: Eddie Cai <eddie.cai.linux at gmail.com>
Reviewed-by: Stefan Brüns <stefan.bruens at rwth-aachen.de>
---
 drivers/usb/host/dwc2.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/usb/host/dwc2.c b/drivers/usb/host/dwc2.c
index 5ac602e..f295843 100644
--- a/drivers/usb/host/dwc2.c
+++ b/drivers/usb/host/dwc2.c
@@ -811,12 +811,19 @@ static int transfer_chunk(struct dwc2_hc_regs *hc_regs, void *aligned_buffer,
 	       (*pid << DWC2_HCTSIZ_PID_OFFSET),
 	       &hc_regs->hctsiz);
 
-	if (!in && xfer_len) {
-		memcpy(aligned_buffer, buffer, xfer_len);
-
-		flush_dcache_range((unsigned long)aligned_buffer,
-				   (unsigned long)aligned_buffer +
-				   roundup(xfer_len, ARCH_DMA_MINALIGN));
+	if (xfer_len) {
+		if (in) {
+			invalidate_dcache_range(
+					(uintptr_t)aligned_buffer,
+					(uintptr_t)aligned_buffer +
+					roundup(xfer_len, ARCH_DMA_MINALIGN));
+		} else {
+			memcpy(aligned_buffer, buffer, xfer_len);
+			flush_dcache_range(
+					(uintptr_t)aligned_buffer,
+					(uintptr_t)aligned_buffer +
+					roundup(xfer_len, ARCH_DMA_MINALIGN));
+		}
 	}
 
 	writel(phys_to_bus((unsigned long)aligned_buffer), &hc_regs->hcdma);
-- 
2.10.2