Set allow_cache_hints to 1 for the vb2_queue capture queue in the STM32MP15xx DCMI V4L2 driver. This allows us to allocate buffers with the V4L2_MEMORY_FLAG_NON_COHERENT set. On STM32MP15xx SoCs, this enables caching for this memory, which improves performance when being read from CPU.

This change should be safe from race conditions since videobuf2 already invalidates or flushes the appropriate cache lines in its prepare() and finish() methods.

Tested on a STM32MP157F SoC. Resulted in 4x buffer access speedup.

Signed-off-by: Marek Vasut marex@denx.de --- Cc: "Christian König" christian.koenig@amd.com Cc: Alexandre Torgue alexandre.torgue@foss.st.com Cc: Hugues Fruchet hugues.fruchet@foss.st.com Cc: Mauro Carvalho Chehab mchehab@kernel.org Cc: Maxime Coquelin mcoquelin.stm32@gmail.com Cc: Philipp Zabel p.zabel@pengutronix.de Cc: Sumit Semwal sumit.semwal@linaro.org Cc: dri-devel@lists.freedesktop.org Cc: linaro-mm-sig@lists.linaro.org Cc: linux-arm-kernel@lists.infradead.org Cc: linux-media@vger.kernel.org Cc: linux-stm32@st-md-mailman.stormreply.com --- drivers/media/platform/st/stm32/stm32-dcmi.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/drivers/media/platform/st/stm32/stm32-dcmi.c b/drivers/media/platform/st/stm32/stm32-dcmi.c index ad8e9742e1ae7..2ac508da5ba36 100644 --- a/drivers/media/platform/st/stm32/stm32-dcmi.c +++ b/drivers/media/platform/st/stm32/stm32-dcmi.c @@ -2084,6 +2084,7 @@ static int dcmi_probe(struct platform_device *pdev) q->mem_ops = &vb2_dma_contig_memops; q->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_MONOTONIC; q->min_buffers_needed = 2; + q->allow_cache_hints = 1; q->dev = &pdev->dev;

ret = vb2_queue_init(q);