[U-Boot] [PATCH v4 4/4] usb: dwc2 : invalidate dcache before starting DMA

[Ziyuan Xu]

From: Xu Ziyuan <xzy.xu at rock-chips.com>

Invalidate dcache before starting the DMA to ensure coherency. 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: Ziyuan Xu <xzy.xu at rock-chips.com>

---

Changes in v4: None
Changes in v3:
- New commit since v3 to fix the coherence issue between memory and
cache

Changes in v2: None

 drivers/usb/gadget/dwc2_udc_otg_xfer_dma.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/usb/gadget/dwc2_udc_otg_xfer_dma.c b/drivers/usb/gadget/dwc2_udc_otg_xfer_dma.c
index 12f5c85..0d6d2fb 100644
--- a/drivers/usb/gadget/dwc2_udc_otg_xfer_dma.c
+++ b/drivers/usb/gadget/dwc2_udc_otg_xfer_dma.c
@@ -110,6 +110,9 @@ static int setdma_rx(struct dwc2_ep *ep, struct dwc2_request *req)
 
 	ctrl =  readl(&reg->out_endp[ep_num].doepctl);
 
+	invalidate_dcache_range((unsigned long) ep->dma_buf,
+				(unsigned long) ep->dma_buf + ep->len);
+
 	writel((unsigned int) ep->dma_buf, &reg->out_endp[ep_num].doepdma);
 	writel(DOEPT_SIZ_PKT_CNT(pktcnt) | DOEPT_SIZ_XFER_SIZE(length),
 	       &reg->out_endp[ep_num].doeptsiz);
-- 
1.9.1