[PATCH] drm/ast: Reload gamma LUT after changing primary plane's color format

[Daniel Vetter]

On Tue, Sep 22, 2020 at 04:46:55PM +0200, Thomas Zimmermann wrote:
> The gamma LUT has to be reloaded after changing the primary plane's
> color format. This used to be done implicitly by the CRTC atomic_enable()
> helper after updating the primary plane. With the recent reordering of
> the steps, the primary plane's setup was moved last and invalidated
> the gamma LUT. Fix this by setting the LUT from within atomic_flush().
> 
> Signed-off-by: Thomas Zimmermann <tzimmermann at suse.de>
> Fixes: 2f0ddd89fe32 ("drm/ast: Enable CRTC before planes")
> Cc: Thomas Zimmermann <tzimmermann at suse.de>
> Cc: Daniel Vetter <daniel.vetter at ffwll.ch>
> Cc: Dave Airlie <airlied at redhat.com>
> Cc: dri-devel at lists.freedesktop.org

Does what it says in the commit message, and makes sense.

Maybe add a comment to the load_lut function or where it's called stating
that this must be done after every plane color change, seems like an
important piece of information to carry around in the code itself and not
just in the commit message.

Either way: Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>

> ---
>  drivers/gpu/drm/ast/ast_mode.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/ast/ast_mode.c b/drivers/gpu/drm/ast/ast_mode.c
> index 834a156e3a75..ba3bf76e104d 100644
> --- a/drivers/gpu/drm/ast/ast_mode.c
> +++ b/drivers/gpu/drm/ast/ast_mode.c
> @@ -742,7 +742,6 @@ static void ast_crtc_dpms(struct drm_crtc *crtc, int mode)
>  	case DRM_MODE_DPMS_SUSPEND:
>  		if (ast->tx_chip_type == AST_TX_DP501)
>  			ast_set_dp501_video_output(crtc->dev, 1);
> -		ast_crtc_load_lut(ast, crtc);
>  		break;
>  	case DRM_MODE_DPMS_OFF:
>  		if (ast->tx_chip_type == AST_TX_DP501)
> @@ -777,6 +776,17 @@ static int ast_crtc_helper_atomic_check(struct drm_crtc *crtc,
>  	return 0;
>  }
>  
> +static void
> +ast_crtc_helper_atomic_flush(struct drm_crtc *crtc, struct drm_crtc_state *old_crtc_state)
> +{
> +	struct ast_private *ast = to_ast_private(crtc->dev);
> +	struct ast_crtc_state *ast_crtc_state = to_ast_crtc_state(crtc->state);
> +	struct ast_crtc_state *old_ast_crtc_state = to_ast_crtc_state(old_crtc_state);
> +
> +	if (old_ast_crtc_state->format != ast_crtc_state->format)
> +		ast_crtc_load_lut(ast, crtc);
> +}
> +
>  static void
>  ast_crtc_helper_atomic_enable(struct drm_crtc *crtc,
>  			      struct drm_crtc_state *old_crtc_state)
> @@ -830,6 +840,7 @@ ast_crtc_helper_atomic_disable(struct drm_crtc *crtc,
>  
>  static const struct drm_crtc_helper_funcs ast_crtc_helper_funcs = {
>  	.atomic_check = ast_crtc_helper_atomic_check,
> +	.atomic_flush = ast_crtc_helper_atomic_flush,
>  	.atomic_enable = ast_crtc_helper_atomic_enable,
>  	.atomic_disable = ast_crtc_helper_atomic_disable,
>  };
> -- 
> 2.28.0
> 

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