linux-kernel - Re: [PATCH 5/6] drm/vc4: Make sure that planes aren't scaled.

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Date:	Fri, 23 Oct 2015 13:24:56 +0200
From:	Daniel Vetter <daniel@...ll.ch>
To:	Eric Anholt <eric@...olt.net>
Cc:	dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 5/6] drm/vc4: Make sure that planes aren't scaled.

On Fri, Oct 23, 2015 at 11:32:35AM +0100, Eric Anholt wrote:
> We would scan out the memory around them if an upscale was attempted,
> and would just scan out incorrectly for downscaling.
> 
> Signed-off-by: Eric Anholt <eric@...olt.net>
> ---
> 
> It looks like, while modetest only wants to set scaling on overlay
> planes, one could do so on our primary/cursor planes if the fd was in
> universal planes mode.
> 
>  drivers/gpu/drm/vc4/vc4_plane.c | 10 ++++++++++
>  1 file changed, 10 insertions(+)
> 
> diff --git a/drivers/gpu/drm/vc4/vc4_plane.c b/drivers/gpu/drm/vc4/vc4_plane.c
> index 2db5092..887f3ca 100644
> --- a/drivers/gpu/drm/vc4/vc4_plane.c
> +++ b/drivers/gpu/drm/vc4/vc4_plane.c
> @@ -157,6 +157,16 @@ static int vc4_plane_mode_set(struct drm_plane *plane,
>  	int crtc_w = state->crtc_w;
>  	int crtc_h = state->crtc_h;
>  
> +	if (state->crtc_w << 16 != state->src_w ||
> +	    state->crtc_h << 16 != state->src_h) {
> +		/* We don't support scaling yet, which involves
> +		 * allocating the LBM memory for scaling temporary
> +		 * storage, and putting filter kernels in the HVS
> +		 * context.
> +		 */
> +		return -EINVAL;
> +	}

Just aside: There's drm_plane_helper_check_update for the common cases.
Unfortunately it suffers a bit from a bikeshed since it wants struct
drm_rect but atomic states don't give you that.
-Daniel

> +
>  	if (crtc_x < 0) {
>  		offset += drm_format_plane_cpp(fb->pixel_format, 0) * -crtc_x;
>  		crtc_w += crtc_x;
> -- 
> 2.6.1
> 
> _______________________________________________
> dri-devel mailing list
> dri-devel@...ts.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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