[PATCH v2] drm/mediatek: Add valid modifier check

[CK Hu (胡俊光)]

Hi, Justin:

On Wed, 2023-07-26 at 15:52 -0400, Justin Green wrote:
>  	 
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>  Add a check to mtk_drm_mode_fb_create() that rejects any modifier
> that
> is not the AFBC mode supported by MT8195's display overlays.
> 
> Tested by booting ChromeOS and verifying the UI works, and by running
> the ChromeOS kms_addfb_basic binary, which has a test called
> "addfb25-bad-modifier" that attempts to create a framebuffer with the
> modifier DRM_FORMAT_MOD_INVALID and verifies the ADDFB2 ioctl returns
> EINVAL.

Reviewed-by: CK Hu <ck.hu at mediatek.com>

> 
> Signed-off-by: Justin Green <greenjustin at chromium.org>
> Tested-by: Fei Shao <fshao at chromium.org>
> ---
> v2:
>  * Replace zero check with comparison to DRM_FORMAT_MOD_LINEAR.
> 
>  drivers/gpu/drm/mediatek/mtk_drm_drv.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> index cd5b18ef7951..2719a1e3163a 100644
> --- a/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> +++ b/drivers/gpu/drm/mediatek/mtk_drm_drv.c
> @@ -51,6 +51,13 @@ mtk_drm_mode_fb_create(struct drm_device *dev,
>  	if (info->num_planes != 1)
>  		return ERR_PTR(-EINVAL);
>  
> +	if (cmd->modifier[0] != DRM_FORMAT_MOD_LINEAR &&
> +	    cmd->modifier[0] != DRM_FORMAT_MOD_ARM_AFBC(
> +					AFBC_FORMAT_MOD_BLOCK_SIZE_32x8
> |
> +					AFBC_FORMAT_MOD_SPLIT |
> +					AFBC_FORMAT_MOD_SPARSE))
> +		return ERR_PTR(-EINVAL);
> +
>  	return drm_gem_fb_create(dev, file, cmd);
>  }
>  
> -- 
> 2.41.0.487.g6d72f3e995-goog