linux-kernel - Re: [PATCH v9 10/32] drm: mediatek: use common helper for a scatterlist contiguity check

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Message-ID: <CAAOTY_9=GFMW2QQKjxWHeZLYTDo3+=j=wZ62t9LrSkfD79ji9A@mail.gmail.com>
Date:   Wed, 2 Sep 2020 06:59:14 +0800
From:   Chun-Kuang Hu <chunkuang.hu@...nel.org>
To:     Marek Szyprowski <m.szyprowski@...sung.com>
Cc:     DRI Development <dri-devel@...ts.freedesktop.org>,
        iommu@...ts.linux-foundation.org, linaro-mm-sig@...ts.linaro.org,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Christoph Hellwig <hch@....de>,
        Robin Murphy <robin.murphy@....com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Chun-Kuang Hu <chunkuang.hu@...nel.org>,
        Philipp Zabel <p.zabel@...gutronix.de>,
        "moderated list:ARM/Mediatek SoC support" 
        <linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH v9 10/32] drm: mediatek: use common helper for a
 scatterlist contiguity check

Hi, Marek:

Marek Szyprowski <m.szyprowski@...sung.com> 於 2020年8月26日 週三 下午2:35寫道：
>
> Use common helper for checking the contiguity of the imported dma-buf and
> do this check before allocating resources, so the error path is simpler.
>

Acked-by: Chun-Kuang Hu <chunkuang.hu@...nel.org>

> Signed-off-by: Marek Szyprowski <m.szyprowski@...sung.com>
> ---
>  drivers/gpu/drm/mediatek/mtk_drm_gem.c | 28 ++++++--------------------
>  1 file changed, 6 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_gem.c b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> index 6190cc3b7b0d..3654ec732029 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_gem.c
> @@ -212,37 +212,21 @@ struct drm_gem_object *mtk_gem_prime_import_sg_table(struct drm_device *dev,
>                         struct dma_buf_attachment *attach, struct sg_table *sg)
>  {
>         struct mtk_drm_gem_obj *mtk_gem;
> -       int ret;
> -       struct scatterlist *s;
> -       unsigned int i;
> -       dma_addr_t expected;
>
> -       mtk_gem = mtk_drm_gem_init(dev, attach->dmabuf->size);
> +       /* check if the entries in the sg_table are contiguous */
> +       if (drm_prime_get_contiguous_size(sg) < attach->dmabuf->size) {
> +               DRM_ERROR("sg_table is not contiguous");
> +               return ERR_PTR(-EINVAL);
> +       }
>
> +       mtk_gem = mtk_drm_gem_init(dev, attach->dmabuf->size);
>         if (IS_ERR(mtk_gem))
>                 return ERR_CAST(mtk_gem);
>
> -       expected = sg_dma_address(sg->sgl);
> -       for_each_sg(sg->sgl, s, sg->nents, i) {
> -               if (!sg_dma_len(s))
> -                       break;
> -
> -               if (sg_dma_address(s) != expected) {
> -                       DRM_ERROR("sg_table is not contiguous");
> -                       ret = -EINVAL;
> -                       goto err_gem_free;
> -               }
> -               expected = sg_dma_address(s) + sg_dma_len(s);
> -       }
> -
>         mtk_gem->dma_addr = sg_dma_address(sg->sgl);
>         mtk_gem->sg = sg;
>
>         return &mtk_gem->base;
> -
> -err_gem_free:
> -       kfree(mtk_gem);
> -       return ERR_PTR(ret);
>  }
>
>  void *mtk_drm_gem_prime_vmap(struct drm_gem_object *obj)
> --
> 2.17.1
>