Re: [PATCH] drm/i915: avoid full modeset when changing the color range properties

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Apr 19, 2013 at 05:26:27PM +0200, Daniel Vetter wrote:
> Automatic color range selection was added in
> 
> commit 55bc60db5988c8366751d3d04dd690698a53412c
> Author: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Date:   Thu Jan 17 16:31:29 2013 +0200
> 
>     drm/i915: Add "Automatic" mode for the "Broadcast RGB" property
> 
> but that removed the check to avoid a full modeset if the value is
> unchanged. Unfortunately X sets all properties with their current
> value at start-up, resulting in some ugly flickering which shouldn't
> be there.

How silly of me to drop the unchanged check.

> 
> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
> Cc: Paulo Zanoni <paulo.r.zanoni@intel.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
> ---
>  drivers/gpu/drm/i915/intel_dp.c   | 8 ++++++++
>  drivers/gpu/drm/i915/intel_hdmi.c | 8 ++++++++
>  drivers/gpu/drm/i915/intel_sdvo.c | 8 ++++++++
>  3 files changed, 24 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 50a9d9f..be529da 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -2666,6 +2666,9 @@ intel_dp_set_property(struct drm_connector *connector,
>  	}
>  
>  	if (property == dev_priv->broadcast_rgb_property) {
> +		bool old_auto = intel_dp->color_range_auto;
> +		bool old_range = intel_dp->color_range;

This looks like it shouldn't work.

We have these guys:
#define   HDMI_COLOR_RANGE_16_235               (1 << 8) /* HDMI only */
#define   DP_COLOR_RANGE_16_235         (1 << 8)

When assigned to bool they become true (== 1), and then that gets
promoted to uint32_t for the comparison below, so it will never match.

> +
>  		switch (val) {
>  		case INTEL_BROADCAST_RGB_AUTO:
>  			intel_dp->color_range_auto = true;
> @@ -2681,6 +2684,11 @@ intel_dp_set_property(struct drm_connector *connector,
>  		default:
>  			return -EINVAL;
>  		}
> +
> +		if (old_auto == intel_dp->color_range_auto &&
> +		    old_range == intel_dp->color_range)
> +			return 0;
> +
>  		goto done;
>  	}
>  
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index 3942041..40d5812 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -947,6 +947,9 @@ intel_hdmi_set_property(struct drm_connector *connector,
>  	}
>  
>  	if (property == dev_priv->broadcast_rgb_property) {
> +		bool old_auto = intel_hdmi->color_range_auto;
> +		bool old_range = intel_hdmi->color_range;
> +
>  		switch (val) {
>  		case INTEL_BROADCAST_RGB_AUTO:
>  			intel_hdmi->color_range_auto = true;
> @@ -962,6 +965,11 @@ intel_hdmi_set_property(struct drm_connector *connector,
>  		default:
>  			return -EINVAL;
>  		}
> +
> +		if (old_auto == intel_hdmi->color_range_auto &&
> +		    old_range == intel_hdmi->color_range)
> +			return 0;
> +
>  		goto done;
>  	}
>  
> diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
> index a618a6a..c1f7e0a 100644
> --- a/drivers/gpu/drm/i915/intel_sdvo.c
> +++ b/drivers/gpu/drm/i915/intel_sdvo.c
> @@ -1930,6 +1930,9 @@ intel_sdvo_set_property(struct drm_connector *connector,
>  	}
>  
>  	if (property == dev_priv->broadcast_rgb_property) {
> +		bool old_auto = intel_sdvo->color_range_auto;
> +		bool old_range = intel_sdvo->color_range;
> +
>  		switch (val) {
>  		case INTEL_BROADCAST_RGB_AUTO:
>  			intel_sdvo->color_range_auto = true;
> @@ -1947,6 +1950,11 @@ intel_sdvo_set_property(struct drm_connector *connector,
>  		default:
>  			return -EINVAL;
>  		}
> +
> +		if (old_auto == intel_sdvo->color_range_auto &&
> +		    old_range == intel_sdvo->color_range)
> +			return 0;
> +
>  		goto done;
>  	}
>  
> -- 
> 1.7.11.7

-- 
Ville Syrjälä
Intel OTC