Re: [Intel-gfx] [PATCH v2 07/11] drm/i915: Allow an arbitrary number of 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>
>
> Remove the "two fixed modes only" limit and grab as many
> downclock modes from the EDID as we can find.
>
> 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 | 42 +++++++---------------
>  1 file changed, 12 insertions(+), 30 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
> index 5d08b2bf27ec..d359c8050fdc 100644
> --- a/drivers/gpu/drm/i915/display/intel_panel.c
> +++ b/drivers/gpu/drm/i915/display/intel_panel.c
> @@ -159,42 +159,24 @@ static bool is_downclock_mode(const struct drm_display_mode *downclock_mode,
>  		downclock_mode->clock < fixed_mode->clock;
>  }
>  
> -static void intel_panel_add_edid_downclock_mode(struct intel_connector *connector)
> +static void intel_panel_add_edid_downclock_modes(struct intel_connector *connector)
>  {
>  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>  	const struct drm_display_mode *fixed_mode =
>  		intel_panel_preferred_fixed_mode(connector);
> -	struct drm_display_mode *scan, *best_mode = NULL;
> -	int best_clock = fixed_mode->clock;
> -
> -	list_for_each_entry(scan, &connector->base.probed_modes, head) {
> -		/*
> -		 * If one mode has the same resolution with the fixed_panel
> -		 * mode while they have the different refresh rate, it means
> -		 * that the reduced downclock is found. In such
> -		 * case we can set the different FPx0/1 to dynamically select
> -		 * between low and high frequency.
> -		 */
> -		if (is_downclock_mode(scan, fixed_mode) &&
> -		    scan->clock < best_clock) {
> -			/*
> -			 * The downclock is already found. But we
> -			 * expect to find the lower downclock.
> -			 */
> -			best_clock = scan->clock;
> -			best_mode = scan;
> -		}
> -	}
> +	struct drm_display_mode *mode, *next;
>  
> -	if (!best_mode)
> -		return;
> +	list_for_each_entry_safe(mode, next, &connector->base.probed_modes, head) {
> +		if (!is_downclock_mode(mode, fixed_mode))
> +			continue;
>  
> -	drm_dbg_kms(&dev_priv->drm,
> -		    "[CONNECTOR:%d:%s] using EDID downclock mode: " DRM_MODE_FMT "\n",
> -		    connector->base.base.id, connector->base.name,
> -		    DRM_MODE_ARG(best_mode));
> +		drm_dbg_kms(&dev_priv->drm,
> +			    "[CONNECTOR:%d:%s] using EDID downclock mode: " DRM_MODE_FMT "\n",
> +			    connector->base.base.id, connector->base.name,
> +			    DRM_MODE_ARG(mode));
>  
> -	list_move_tail(&best_mode->head, &connector->panel.fixed_modes);
> +		list_move_tail(&mode->head, &connector->panel.fixed_modes);
> +	}
>  }
>  
>  static void intel_panel_add_edid_fixed_mode(struct intel_connector *connector)
> @@ -243,7 +225,7 @@ 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_add_edid_downclock_modes(connector);
>  	intel_panel_destroy_probed_modes(connector);
>  }

-- 
Jani Nikula, Intel Open Source Graphics Center