This small series adds support for non-coherent video capture buffers on Rockchip ISP V1. Patch 1 fixes cache management for dmabuf's allocated by dma-contig allocator. Patch 2 allows non-coherent allocations on the rkisp1 capture queue. Some timing measurements are provided in the commit message of patch 2.
Signed-off-by: Mikhail Rudenko mike.rudenko@gmail.com --- Changes in v3: - ignore skip_cache_sync_* flags in vb2_dc_dmabuf_ops_{begin,end}_cpu_access - invalidate/flush kernel mappings as appropriate if they exist - use dma_sync_sgtable_* instead of dma_sync_sg_* - Link to v2: https://lore.kernel.org/r/20250115-b4-rkisp-noncoherent-v2-0-0853e1a24012@gm...
Changes in v2: - Fix vb2_dc_dmabuf_ops_{begin,end}_cpu_access() for non-coherent buffers. - Add cache management timing information to patch 2 commit message. - Link to v1: https://lore.kernel.org/r/20250102-b4-rkisp-noncoherent-v1-1-bba164f7132c@gm...
--- Mikhail Rudenko (2): media: videobuf2: Fix dmabuf cache sync/flush in dma-contig media: rkisp1: Allow non-coherent video capture buffers
.../media/common/videobuf2/videobuf2-dma-contig.c | 22 ++++++++++++++++++++++ .../platform/rockchip/rkisp1/rkisp1-capture.c | 1 + 2 files changed, 23 insertions(+) --- base-commit: c4b7779abc6633677e6edb79e2809f4f61fde157 change-id: 20241231-b4-rkisp-noncoherent-ad6e7c7a68ba
Best regards,
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@vger.kernel.org Signed-off-by: Mikhail Rudenko mike.rudenko@gmail.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 bb0b7fa67b539aa73ad5ccf3c3bc318e26f8a4cb..146d7997a0da5989fb081a6f28ce0641fe726e63 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, buf->dma_dir); + 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, buf->dma_dir); + return 0; }
On Tue, Jan 28, 2025 at 9:36 PM Mikhail Rudenko mike.rudenko@gmail.com wrote:
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@vger.kernel.org Signed-off-by: Mikhail Rudenko mike.rudenko@gmail.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 bb0b7fa67b539aa73ad5ccf3c3bc318e26f8a4cb..146d7997a0da5989fb081a6f28ce0641fe726e63 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, buf->dma_dir);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, buf->dma_dir);return 0;}
I took some time (over)thinking the kernel vmap range synchronization, because these functions can be called both from the kernel space using respective dma_buf_*() kAPI and also from the user space using the DMA_BUF_SYNC IOCTLs, so we could in theory have the multiple invocations racing with each other, but then I realized that we don't really provide any guarantees for concurrent writes and reads from the CPU, so I believe this should work fine. Sorry for the delay.
Acked-by: Tomasz Figa tfiga@chromium.org
Let me add @Christoph Hellwig and @Robin Murphy just in case I'm wrong on that, though... Hans, let's give them some time to take a look before applying this.
Best regards, Tomasz
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Mikhail Rudenko -
Tomasz Figa