Re: [PATCH] mediatek/vcodec: Enable incoherent buffer allocation

[Sergey Senozhatsky <senozhatsky@chromium.org>]

On (22/05/31 17:10), Justin Green wrote:
> Set allow_cache_hints to 1 for the vb2_queue source and destination queues
> in the mediatek vcodec V4L2 driver. This allows us to allocate buffers
> with the V4L2_MEMORY_FLAG_NON_COHERENT set. On Mediatek SoCs, this enables
> caching for this memory, which vastly improves performance when being read
> from CPU. Read performance for these buffers is in turn important for
> detiling MM21 video frames in software.
> 
> 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 MT8183 SoC. Resulted in both correct detiling and a 10X
> speedup.

Hi Justin,

It seems that something has happened to tabs and code formatting,
could you double check and resend?

> @@ -929,30 +929,32 @@ int mtk_vcodec_dec_queue_init(void *priv, struct
> vb2_queue *src_vq,
> 
>   mtk_v4l2_debug(3, "[%d]", ctx->id);
> 
> - src_vq->type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
> - src_vq->io_modes = VB2_DMABUF | VB2_MMAP;
> - src_vq->drv_priv = ctx;
> - src_vq->buf_struct_size = sizeof(struct mtk_video_dec_buf);
> - src_vq->ops = ctx->dev->vdec_pdata->vdec_vb2_ops;
> - src_vq->mem_ops = &vb2_dma_contig_memops;
> - src_vq->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
> - src_vq->lock = &ctx->dev->dev_mutex;
> - src_vq->dev             = &ctx->dev->plat_dev->dev;
> + src_vq->type   = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
> + src_vq->io_modes   = VB2_DMABUF | VB2_MMAP;
> + src_vq->drv_priv   = ctx;
> + src_vq->buf_struct_size   = sizeof(struct mtk_video_dec_buf);
> + src_vq->ops   = ctx->dev->vdec_pdata->vdec_vb2_ops;
> + src_vq->mem_ops   = &vb2_dma_contig_memops;
> + src_vq->timestamp_flags   = V4L2_BUF_FLAG_TIMESTAMP_COPY;
> + src_vq->lock   = &ctx->dev->dev_mutex;
> + src_vq->dev               = &ctx->dev->plat_dev->dev;
> + src_vq->allow_cache_hints = 1;

I guess it should look something like this

-	src_vq->type		= V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
-	src_vq->io_modes	= VB2_DMABUF | VB2_MMAP;
-	src_vq->drv_priv	= ctx;
-	src_vq->buf_struct_size = sizeof(struct mtk_video_dec_buf);
-	src_vq->ops		= ctx->dev->vdec_pdata->vdec_vb2_ops;
-	src_vq->mem_ops		= &vb2_dma_contig_memops;
-	src_vq->timestamp_flags = V4L2_BUF_FLAG_TIMESTAMP_COPY;
-	src_vq->lock		= &ctx->dev->dev_mutex;
-	src_vq->dev             = &ctx->dev->plat_dev->dev;
+	src_vq->type			= V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+	src_vq->io_modes		= VB2_DMABUF | VB2_MMAP;
+	src_vq->drv_priv		= ctx;
+	src_vq->buf_struct_size		= sizeof(struct mtk_video_dec_buf);
+	src_vq->ops			= ctx->dev->vdec_pdata->vdec_vb2_ops;
+	src_vq->mem_ops			= &vb2_dma_contig_memops;
+	src_vq->timestamp_flags		= V4L2_BUF_FLAG_TIMESTAMP_COPY;
+	src_vq->lock			= &ctx->dev->dev_mutex;
+	src_vq->dev			= &ctx->dev->plat_dev->dev;
+	src_vq->allow_cache_hints	= 1;