Re: [PATCH 2/2] drm/ingenic: Don't request full modeset if property is not modified

[Maxime Ripard <maxime@cerno.tech>]

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Hi,

On Mon, Mar 29, 2021 at 06:50:46PM +0100, Paul Cercueil wrote:
> Avoid requesting a full modeset if the sharpness property is not
> modified, because then we don't actually need it.
> 
> Fixes: fc1acf317b01 ("drm/ingenic: Add support for the IPU")
> Cc: <stable@vger.kernel.org> # 5.8+
> Signed-off-by: Paul Cercueil <paul@crapouillou.net>
> ---
>  drivers/gpu/drm/ingenic/ingenic-ipu.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/ingenic/ingenic-ipu.c b/drivers/gpu/drm/ingenic/ingenic-ipu.c
> index 3b1091e7c0cd..95b665c4a7b0 100644
> --- a/drivers/gpu/drm/ingenic/ingenic-ipu.c
> +++ b/drivers/gpu/drm/ingenic/ingenic-ipu.c
> @@ -640,10 +640,12 @@ ingenic_ipu_plane_atomic_set_property(struct drm_plane *plane,
>  {
>  	struct ingenic_ipu *ipu = plane_to_ingenic_ipu(plane);
>  	struct drm_crtc_state *crtc_state;
> +	bool mode_changed;
>  
>  	if (property != ipu->sharpness_prop)
>  		return -EINVAL;
>  
> +	mode_changed = val != ipu->sharpness;
>  	ipu->sharpness = val;
>  
>  	if (state->crtc) {
> @@ -651,7 +653,7 @@ ingenic_ipu_plane_atomic_set_property(struct drm_plane *plane,
>  		if (WARN_ON(!crtc_state))
>  			return -EINVAL;
>  
> -		crtc_state->mode_changed = true;
> +		crtc_state->mode_changed |= mode_changed;
>  	}

I'd just change the condition from

if (state->crtc)

to

if (state->crtc && val != ipu->sharpness)

It's going to be easier to extend if you ever need to. Also, drivers
usually do this in atomic_check, is there a specific reason to do it in
atomic_set_property?

Maxime

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