Re: [Intel-gfx] [PATCH v2 06/11] drm/i915: Stop duplicating the EDID fixed/downclock modes

[Jani Nikula <jani.nikula@linux.intel.com>]

On Thu, 31 Mar 2022, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Instead of duplicating the fixed/downclock modes we can just grab
> the originals straight from the probed_modes list and keep them.
> The next .get_modes() is going to repopulate the probed_modes list
> anyway so whatever we leave there is just going to sit around until
> that time wasting memory. In fact let's clear out the probed modes
> list entirely to make sure we get 100% consistent behaviour starting
> already from the very first real .get_modes().
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_panel.c | 62 ++++++++++------------
>  1 file changed, 29 insertions(+), 33 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
> index 3b1da9aa023f..5d08b2bf27ec 100644
> --- a/drivers/gpu/drm/i915/display/intel_panel.c
> +++ b/drivers/gpu/drm/i915/display/intel_panel.c
> @@ -164,8 +164,7 @@ static void intel_panel_add_edid_downclock_mode(struct intel_connector *connecto
>  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>  	const struct drm_display_mode *fixed_mode =
>  		intel_panel_preferred_fixed_mode(connector);
> -	const struct drm_display_mode *scan, *best_mode = NULL;
> -	struct drm_display_mode *downclock_mode;
> +	struct drm_display_mode *scan, *best_mode = NULL;
>  	int best_clock = fixed_mode->clock;
>  
>  	list_for_each_entry(scan, &connector->base.probed_modes, head) {
> @@ -190,58 +189,54 @@ static void intel_panel_add_edid_downclock_mode(struct intel_connector *connecto
>  	if (!best_mode)
>  		return;
>  
> -	downclock_mode = drm_mode_duplicate(&dev_priv->drm, best_mode);
> -	if (!downclock_mode)
> -		return;
> -
>  	drm_dbg_kms(&dev_priv->drm,
> -		    "[CONNECTOR:%d:%s] using downclock mode from EDID: " DRM_MODE_FMT "\n",
> +		    "[CONNECTOR:%d:%s] using EDID downclock mode: " DRM_MODE_FMT "\n",
>  		    connector->base.base.id, connector->base.name,
> -		    DRM_MODE_ARG(downclock_mode));
> +		    DRM_MODE_ARG(best_mode));
>  
> -	list_add_tail(&downclock_mode->head, &connector->panel.fixed_modes);
> +	list_move_tail(&best_mode->head, &connector->panel.fixed_modes);
>  }
>  
>  static void intel_panel_add_edid_fixed_mode(struct intel_connector *connector)
>  {
>  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
> -	const struct drm_display_mode *scan;
> -	struct drm_display_mode *fixed_mode;
> +	struct drm_display_mode *scan, *fixed_mode = NULL;
>  
>  	if (list_empty(&connector->base.probed_modes))
>  		return;
>  
> -	/* prefer fixed mode from EDID if available */
> +	/* make sure the preferred mode is first */
>  	list_for_each_entry(scan, &connector->base.probed_modes, head) {
> -		if ((scan->type & DRM_MODE_TYPE_PREFERRED) == 0)
> -			continue;
> -
> -		fixed_mode = drm_mode_duplicate(&dev_priv->drm, scan);
> -		if (!fixed_mode)
> -			return;
> -
> -		drm_dbg_kms(&dev_priv->drm,
> -			    "[CONNECTOR:%d:%s] using preferred mode from EDID: " DRM_MODE_FMT "\n",
> -			    connector->base.base.id, connector->base.name,
> -			    DRM_MODE_ARG(fixed_mode));
> -
> -		list_add_tail(&fixed_mode->head, &connector->panel.fixed_modes);
> -		return;
> +		if (scan->type & DRM_MODE_TYPE_PREFERRED) {
> +			fixed_mode = scan;
> +			break;
> +		}
>  	}
>  
> -	scan = list_first_entry(&connector->base.probed_modes,
> -				typeof(*scan), head);
> -	fixed_mode = drm_mode_duplicate(&dev_priv->drm, scan);
>  	if (!fixed_mode)
> -		return;
> +		fixed_mode = list_first_entry(&connector->base.probed_modes,
> +					      typeof(*fixed_mode), head);
>  
> -	fixed_mode->type |= DRM_MODE_TYPE_PREFERRED;
>  	drm_dbg_kms(&dev_priv->drm,
> -		    "[CONNECTOR:%d:%s] using first mode from EDID: " DRM_MODE_FMT "\n",
> +		    "[CONNECTOR:%d:%s] using %s EDID fixed mode: " DRM_MODE_FMT "\n",
>  		    connector->base.base.id, connector->base.name,
> +		    fixed_mode->type & DRM_MODE_TYPE_PREFERRED ? "preferred" : "first",
>  		    DRM_MODE_ARG(fixed_mode));
>  
> -	list_add_tail(&fixed_mode->head, &connector->panel.fixed_modes);
> +	fixed_mode->type |= DRM_MODE_TYPE_PREFERRED;
> +
> +	list_move_tail(&fixed_mode->head, &connector->panel.fixed_modes);
> +}
> +
> +static void intel_panel_destroy_probed_modes(struct intel_connector *connector)
> +{
> +	struct drm_i915_private *i915 = to_i915(connector->base.dev);
> +	struct drm_display_mode *mode, *next;
> +
> +	list_for_each_entry_safe(mode, next, &connector->base.probed_modes, head) {
> +		list_del(&mode->head);
> +		drm_mode_destroy(&i915->drm, mode);
> +	}
>  }
>  
>  void intel_panel_add_edid_fixed_modes(struct intel_connector *connector, bool has_drrs)
> @@ -249,6 +244,7 @@ void intel_panel_add_edid_fixed_modes(struct intel_connector *connector, bool ha
>  	intel_panel_add_edid_fixed_mode(connector);
>  	if (intel_panel_preferred_fixed_mode(connector) && has_drrs)
>  		intel_panel_add_edid_downclock_mode(connector);
> +	intel_panel_destroy_probed_modes(connector);
>  }
>  
>  static void intel_panel_add_fixed_mode(struct intel_connector *connector,

-- 
Jani Nikula, Intel Open Source Graphics Center