linux-kernel - [Patch 26/35] media: ti-vpe: vpdma: Use bidirectional cached buffers

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Date:   Wed, 28 Sep 2016 16:22:57 -0500
From:   Benoit Parrot <bparrot@...com>
To:     Hans Verkuil <hverkuil@...all.nl>
CC:     <linux-media@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: [Patch 26/35] media: ti-vpe: vpdma: Use bidirectional cached buffers

From: Nikhil Devshatwar <nikhil.nd@...com>

VPDMA buffer will be used by CPU as well as by the VPDMA.
CPU will write/update the VPDMA descriptors containing data
about the video buffer DMA addresses.
VPDMA will write the "write descriptor" containing the
data about the DMA operation.

When mapping/unmapping the buffer, driver has to take care of
WriteBack and invalidation of the cache so that all the
coherency is maintained from both directions.

Use DMA_BIDIRECTIONAL to maintain coherency between CPU and VPDMA.

Signed-off-by: Nikhil Devshatwar <nikhil.nd@...com>
Signed-off-by: Benoit Parrot <bparrot@...com>
---
 drivers/media/platform/ti-vpe/vpdma.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/media/platform/ti-vpe/vpdma.c b/drivers/media/platform/ti-vpe/vpdma.c
index 54c1174cad75..e8ed6bae83ed 100644
--- a/drivers/media/platform/ti-vpe/vpdma.c
+++ b/drivers/media/platform/ti-vpe/vpdma.c
@@ -367,7 +367,7 @@ int vpdma_map_desc_buf(struct vpdma_data *vpdma, struct vpdma_buf *buf)
 
 	WARN_ON(buf->mapped);
 	buf->dma_addr = dma_map_single(dev, buf->addr, buf->size,
-				DMA_TO_DEVICE);
+				DMA_BIDIRECTIONAL);
 	if (dma_mapping_error(dev, buf->dma_addr)) {
 		dev_err(dev, "failed to map buffer\n");
 		return -EINVAL;
@@ -388,7 +388,8 @@ void vpdma_unmap_desc_buf(struct vpdma_data *vpdma, struct vpdma_buf *buf)
 	struct device *dev = &vpdma->pdev->dev;
 
 	if (buf->mapped)
-		dma_unmap_single(dev, buf->dma_addr, buf->size, DMA_TO_DEVICE);
+		dma_unmap_single(dev, buf->dma_addr, buf->size,
+				DMA_BIDIRECTIONAL);
 
 	buf->mapped = false;
 }
-- 
2.9.0