linux-kernel - [PATCH v4 1/2] media: videobuf2: Fix dmabuf cache sync/flush in dma-contig

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Message-Id: <20250303-b4-rkisp-noncoherent-v4-1-e32e843fb6ef@gmail.com>
Date: Mon, 03 Mar 2025 14:40:09 +0300
From: Mikhail Rudenko <mike.rudenko@...il.com>
To: Dafna Hirschfeld <dafna@...tmail.com>, 
 Laurent Pinchart <laurent.pinchart@...asonboard.com>, 
 Mauro Carvalho Chehab <mchehab@...nel.org>, 
 Heiko Stuebner <heiko@...ech.de>, Tomasz Figa <tfiga@...omium.org>, 
 Marek Szyprowski <m.szyprowski@...sung.com>, 
 Hans Verkuil <hverkuil@...all.nl>, 
 Sergey Senozhatsky <senozhatsky@...omium.org>
Cc: linux-media@...r.kernel.org, linux-rockchip@...ts.infradead.org, 
 linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
 Mauro Carvalho Chehab <mchehab+huawei@...nel.org>, 
 Mikhail Rudenko <mike.rudenko@...il.com>, stable@...r.kernel.org
Subject: [PATCH v4 1/2] media: videobuf2: Fix dmabuf cache sync/flush in
 dma-contig

When support for V4L2_FLAG_MEMORY_NON_CONSISTENT was removed in
commit 129134e5415d ("media: media/v4l2: remove
V4L2_FLAG_MEMORY_NON_CONSISTENT flag"),
vb2_dc_dmabuf_ops_{begin,end}_cpu_access() functions were made
no-ops. Later, when support for V4L2_MEMORY_FLAG_NON_COHERENT was
introduced in commit c0acf9cfeee0 ("media: videobuf2: handle
V4L2_MEMORY_FLAG_NON_COHERENT flag"), the above functions remained
no-ops, making cache maintenance for non-coherent dmabufs allocated by
dma-contig impossible.

Fix this by reintroducing dma_sync_sgtable_for_{cpu,device} and
{flush,invalidate}_kernel_vmap_range calls to
vb2_dc_dmabuf_ops_{begin,end}_cpu_access() functions for non-coherent
buffers.

Fixes: c0acf9cfeee0 ("media: videobuf2: handle V4L2_MEMORY_FLAG_NON_COHERENT flag")
Cc: stable@...r.kernel.org
Signed-off-by: Mikhail Rudenko <mike.rudenko@...il.com>
---
 .../media/common/videobuf2/videobuf2-dma-contig.c  | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
index a13ec569c82f6da2d977222b94af32e74c6c6c82..d41095fe5bd21faf815d6b035d7bc888a84a95d5 100644
--- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c
+++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
@@ -427,6 +427,17 @@ static int
 vb2_dc_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
 				   enum dma_data_direction direction)
 {
+	struct vb2_dc_buf *buf = dbuf->priv;
+	struct sg_table *sgt = buf->dma_sgt;
+
+	if (!buf->non_coherent_mem)
+		return 0;
+
+	if (buf->vaddr)
+		invalidate_kernel_vmap_range(buf->vaddr, buf->size);
+
+	dma_sync_sgtable_for_cpu(buf->dev, sgt, direction);
+
 	return 0;
 }
 
@@ -434,6 +445,17 @@ static int
 vb2_dc_dmabuf_ops_end_cpu_access(struct dma_buf *dbuf,
 				 enum dma_data_direction direction)
 {
+	struct vb2_dc_buf *buf = dbuf->priv;
+	struct sg_table *sgt = buf->dma_sgt;
+
+	if (!buf->non_coherent_mem)
+		return 0;
+
+	if (buf->vaddr)
+		flush_kernel_vmap_range(buf->vaddr, buf->size);
+
+	dma_sync_sgtable_for_device(buf->dev, sgt, direction);
+
 	return 0;
 }
 

-- 
2.48.1