linux-kernel - Re: [PATCH] media: videobuf2-dma-contig: Invalidate vmap range before DMA range

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Message-ID: <4b337d6c-fac5-5c12-7f62-f70c09fc2518@samsung.com>
Date:   Wed, 19 Jan 2022 09:32:55 +0100
From:   Marek Szyprowski <m.szyprowski@...sung.com>
To:     Sergey Senozhatsky <senozhatsky@...omium.org>,
        Tomasz Figa <tfiga@...omium.org>,
        Hans Verkuil <hverkuil-cisco@...all.nl>
Cc:     Christoph Hellwig <hch@....de>,
        Dafna Hirschfeld <dafna.hirschfeld@...labora.com>,
        Ricardo Ribalda <ribalda@...omium.org>,
        linux-media@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] media: videobuf2-dma-contig: Invalidate vmap range
 before DMA range

On 19.01.2022 09:14, Sergey Senozhatsky wrote:
> Christoph suggests [1] that invalidating vmap range before
> direct mapping range makes more sense.
>
> [1]: https://lore.kernel.org/all/20220111085958.GA22795@lst.de/
> Signed-off-by: Sergey Senozhatsky <senozhatsky@...omium.org>

Right.

Acked-by: Marek Szyprowski <m.szyprowski@...sung.com>

> ---
>   .../media/common/videobuf2/videobuf2-dma-contig.c    | 12 ++++++------
>   1 file changed, 6 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/media/common/videobuf2/videobuf2-dma-contig.c b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> index 7c4096e62173..0e3f264122af 100644
> --- a/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> +++ b/drivers/media/common/videobuf2/videobuf2-dma-contig.c
> @@ -132,12 +132,12 @@ static void vb2_dc_prepare(void *buf_priv)
>   	if (!buf->non_coherent_mem)
>   		return;
>   
> -	/* For both USERPTR and non-coherent MMAP */
> -	dma_sync_sgtable_for_device(buf->dev, sgt, buf->dma_dir);
> -
>   	/* Non-coherent MMAP only */
>   	if (buf->vaddr)
>   		flush_kernel_vmap_range(buf->vaddr, buf->size);
> +
> +	/* For both USERPTR and non-coherent MMAP */
> +	dma_sync_sgtable_for_device(buf->dev, sgt, buf->dma_dir);
>   }
>   
>   static void vb2_dc_finish(void *buf_priv)
> @@ -152,12 +152,12 @@ static void vb2_dc_finish(void *buf_priv)
>   	if (!buf->non_coherent_mem)
>   		return;
>   
> -	/* For both USERPTR and non-coherent MMAP */
> -	dma_sync_sgtable_for_cpu(buf->dev, sgt, buf->dma_dir);
> -
>   	/* Non-coherent MMAP only */
>   	if (buf->vaddr)
>   		invalidate_kernel_vmap_range(buf->vaddr, buf->size);
> +
> +	/* For both USERPTR and non-coherent MMAP */
> +	dma_sync_sgtable_for_cpu(buf->dev, sgt, buf->dma_dir);
>   }
>   
>   /*********************************************/

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland