Re: [Intel-gfx] [PATCH 1/9] drm/i915: Put the downclock_mode check back into can_enable_drrs()

["Souza, Jose" <jose.souza@intel.com>]

On Tue, 2022-03-15 at 15:27 +0200, Ville Syrjala wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> With static DRRS the user might ask for the lowest possible refresh
> rate of the panel, in which case we're not going to find a suitable
> downclock mode for it and we should not try to enable seamless DRRS.
> This will in fact oops.
> 
> We used to check for the presence of the downclock mode here, but
> that got removed in commit f0a57798fb5c ("drm/i915: Introduce
> intel_panel_drrs_type()") as redundant (which it was at the time).
> But we do need the check again now that static DRRS is a thing.
> 
> I must have not re-tested static DRRS fully after introducing
> intel_panel_drrs_type() :/


Reviewed-by: José Roberto de Souza <jose.souza@intel.com>

> 
> Fixes: c5ee23437cae ("drm/i915: Implement static DRRS")
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_drrs.c | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_drrs.c b/drivers/gpu/drm/i915/display/intel_drrs.c
> index 2bbc0388263a..e1b41b772521 100644
> --- a/drivers/gpu/drm/i915/display/intel_drrs.c
> +++ b/drivers/gpu/drm/i915/display/intel_drrs.c
> @@ -62,7 +62,8 @@ const char *intel_drrs_type_str(enum drrs_type drrs_type)
>  }
>  
>  static bool can_enable_drrs(struct intel_connector *connector,
> -			    const struct intel_crtc_state *pipe_config)
> +			    const struct intel_crtc_state *pipe_config,
> +			    const struct drm_display_mode *downclock_mode)
>  {
>  	if (pipe_config->vrr.enable)
>  		return false;
> @@ -76,7 +77,8 @@ static bool can_enable_drrs(struct intel_connector *connector,
>  	if (pipe_config->has_psr)
>  		return false;
>  
> -	return intel_panel_drrs_type(connector) == DRRS_TYPE_SEAMLESS;
> +	return downclock_mode &&
> +		intel_panel_drrs_type(connector) == DRRS_TYPE_SEAMLESS;
>  }
>  
>  void
> @@ -89,7 +91,7 @@ intel_drrs_compute_config(struct intel_connector *connector,
>  		intel_panel_downclock_mode(connector, &pipe_config->hw.adjusted_mode);
>  	int pixel_clock;
>  
> -	if (!can_enable_drrs(connector, pipe_config)) {
> +	if (!can_enable_drrs(connector, pipe_config, downclock_mode)) {
>  		if (intel_cpu_transcoder_has_m2_n2(i915, pipe_config->cpu_transcoder))
>  			intel_zero_m_n(&pipe_config->dp_m2_n2);
>  		return;