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From: Karl Mehltretter <kmehltretter@gmail.com>
To: Tomasz Figa <tfiga@chromium.org>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	Hans de Goede <hansg@kernel.org>,
	Hans Verkuil <hverkuil@kernel.org>,
	Mauro Carvalho Chehab <mchehab@kernel.org>
Cc: "Karl Mehltretter" <kmehltretter@gmail.com>,
	"Christian König" <christian.koenig@amd.com>,
	"Nicolas Dufresne" <nicolas@ndufresne.ca>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
	linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org
Subject: [PATCH v2 2/3] media: uvcvideo: synchronize imported DMA-BUFs for CPU access
Date: Sat,  7 Nov 2026 11:47:02 +0100	[thread overview]
Message-ID: <20261107104703.44111-3-kmehltretter@gmail.com> (raw)
In-Reply-To: <20261107104703.44111-1-kmehltretter@gmail.com>

uvcvideo writes USB payloads into imported DMA-BUFs with the CPU without
cache synchronization, leaving physical RAM stale for non-coherent DMA
importers.

Set uses_cpu_access to bracket the driver's CPU access.

Fixes: ccc4c539c05f ("[media] v4l: uvc: add support for DMABUF importing")
Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
---
 drivers/media/usb/uvc/uvc_queue.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/media/usb/uvc/uvc_queue.c b/drivers/media/usb/uvc/uvc_queue.c
index 3c002c8f442f..1f92ee96e071 100644
--- a/drivers/media/usb/uvc/uvc_queue.c
+++ b/drivers/media/usb/uvc/uvc_queue.c
@@ -247,6 +247,7 @@ int uvc_queue_init(struct uvc_streaming *stream, struct uvc_video_queue *queue,
 	queue->queue.drv_priv = queue;
 	queue->queue.buf_struct_size = sizeof(struct uvc_buffer);
 	queue->queue.mem_ops = &vb2_vmalloc_memops;
+	queue->queue.uses_cpu_access = true;
 	queue->queue.timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC
 		| V4L2_BUF_FLAG_TSTAMP_SRC_SOE;
 	queue->queue.lock = &queue->mutex;
-- 
2.39.5 (Apple Git-154)


  parent reply	other threads:[~2026-11-07 10:47 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-11-07 10:47 [PATCH v2 0/3] media: synchronize CPU access to imported DMA-BUFs Karl Mehltretter
2026-11-07 10:47 ` [PATCH v2 1/3] media: videobuf2: add opt-in DMA-BUF CPU access Karl Mehltretter
2026-11-07 10:47 ` Karl Mehltretter [this message]
2026-11-07 10:47 ` [PATCH v2 3/3] media: vivid: synchronize imported DMA-BUFs for " Karl Mehltretter
2026-11-07 10:59 ` [PATCH v2 0/3] media: synchronize CPU access to imported DMA-BUFs Laurent Pinchart

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