Re: [Intel-gfx] [PATCH v2 08/11] drm/i915: Allow higher refresh rate alternate fixed 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>
>
> We shouldn't restrict ourselves to just downclock modes with
> lower refresh rate than the preferred mode. Laptops these
> days can offer higher refresh rate modes as well.
>
> Remove the arbitrary limit and allow all modes that, apart
> from the clock, match the preferred mode.
>
> Closes: https://gitlab.freedesktop.org/drm/intel/-/issues/125
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_panel.c | 18 +++++++++---------
>  1 file changed, 9 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_panel.c b/drivers/gpu/drm/i915/display/intel_panel.c
> index d359c8050fdc..f3e52e7413fe 100644
> --- a/drivers/gpu/drm/i915/display/intel_panel.c
> +++ b/drivers/gpu/drm/i915/display/intel_panel.c
> @@ -149,29 +149,29 @@ int intel_panel_compute_config(struct intel_connector *connector,
>  	return 0;
>  }
>  
> -static bool is_downclock_mode(const struct drm_display_mode *downclock_mode,
> -			      const struct drm_display_mode *fixed_mode)
> +static bool is_alt_fixed_mode(const struct drm_display_mode *mode,
> +			      const struct drm_display_mode *preferred_mode)
>  {
> -	return drm_mode_match(downclock_mode, fixed_mode,
> +	return drm_mode_match(mode, preferred_mode,
>  			      DRM_MODE_MATCH_TIMINGS |
>  			      DRM_MODE_MATCH_FLAGS |
>  			      DRM_MODE_MATCH_3D_FLAGS) &&
> -		downclock_mode->clock < fixed_mode->clock;
> +		mode->clock != preferred_mode->clock;
>  }
>  
>  static void intel_panel_add_edid_downclock_modes(struct intel_connector *connector)

Nitpick, I guess this is now ill-named.

>  {
>  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
> -	const struct drm_display_mode *fixed_mode =
> +	const struct drm_display_mode *preferred_mode =
>  		intel_panel_preferred_fixed_mode(connector);
>  	struct drm_display_mode *mode, *next;
>  
>  	list_for_each_entry_safe(mode, next, &connector->base.probed_modes, head) {
> -		if (!is_downclock_mode(mode, fixed_mode))
> +		if (!is_alt_fixed_mode(mode, preferred_mode))
>  			continue;
>  
>  		drm_dbg_kms(&dev_priv->drm,
> -			    "[CONNECTOR:%d:%s] using EDID downclock mode: " DRM_MODE_FMT "\n",
> +			    "[CONNECTOR:%d:%s] using alternate EDID fixed mode: " DRM_MODE_FMT "\n",
>  			    connector->base.base.id, connector->base.name,
>  			    DRM_MODE_ARG(mode));
>  
> @@ -179,7 +179,7 @@ static void intel_panel_add_edid_downclock_modes(struct intel_connector *connect
>  	}
>  }
>  
> -static void intel_panel_add_edid_fixed_mode(struct intel_connector *connector)
> +static void intel_panel_add_edid_preferred_mode(struct intel_connector *connector)
>  {
>  	struct drm_i915_private *dev_priv = to_i915(connector->base.dev);
>  	struct drm_display_mode *scan, *fixed_mode = NULL;
> @@ -223,7 +223,7 @@ static void intel_panel_destroy_probed_modes(struct intel_connector *connector)
>  
>  void intel_panel_add_edid_fixed_modes(struct intel_connector *connector, bool has_drrs)
>  {
> -	intel_panel_add_edid_fixed_mode(connector);
> +	intel_panel_add_edid_preferred_mode(connector);
>  	if (intel_panel_preferred_fixed_mode(connector) && has_drrs)
>  		intel_panel_add_edid_downclock_modes(connector);

Nitpick, support for multiple fixed modes still depends on drrs
support. I mean this patch is clearly forward progress, but I'm not sure
if this fully closes the referenced issue. In practical terms it might,
considering the machines with high refresh rate panels are probably
fairly new.

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


>  	intel_panel_destroy_probed_modes(connector);

-- 
Jani Nikula, Intel Open Source Graphics Center