[Intel-gfx] [PATCH v5 4/4] drm/i915: DVO pixel clock check

[Ville Syrjälä]

On Tue, Aug 18, 2015 at 02:37:02PM +0300, Mika Kahola wrote:
> It is possible the we request to have a mode that has
> higher pixel clock than our HW can support. This patch
> checks if requested pixel clock is lower than the one
> supported by the HW. The requested mode is discarded
> if we cannot support the requested pixel clock.
> 
> This patch applies to DVO.
> 
> V2:
> - removed computation for max pixel clock
> 
> V3:
> - cleanup by removing unnecessary lines
> 
> V4:
> - clock check against max dotclock moved inside 'if (fixed_mode)'
> 
> V5:
> - dot clock check against fixed_mode clock when available
> 
> Signed-off-by: Mika Kahola <mika.kahola at intel.com>

Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>

> ---
>  drivers/gpu/drm/i915/intel_dvo.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dvo.c b/drivers/gpu/drm/i915/intel_dvo.c
> index dc532bb..c80fe1f 100644
> --- a/drivers/gpu/drm/i915/intel_dvo.c
> +++ b/drivers/gpu/drm/i915/intel_dvo.c
> @@ -201,6 +201,8 @@ intel_dvo_mode_valid(struct drm_connector *connector,
>  		     struct drm_display_mode *mode)
>  {
>  	struct intel_dvo *intel_dvo = intel_attached_dvo(connector);
> +	int max_dotclk = to_i915(connector->dev)->max_dotclk_freq;
> +	int target_clock = mode->clock;
>  
>  	if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
>  		return MODE_NO_DBLESCAN;
> @@ -212,8 +214,13 @@ intel_dvo_mode_valid(struct drm_connector *connector,
>  			return MODE_PANEL;
>  		if (mode->vdisplay > intel_dvo->panel_fixed_mode->vdisplay)
>  			return MODE_PANEL;
> +
> +		target_clock = intel_dvo->panel_fixed_mode->clock;
>  	}
>  
> +	if (target_clock > max_dotclk)
> +		return MODE_CLOCK_HIGH;
> +
>  	return intel_dvo->dev.dev_ops->mode_valid(&intel_dvo->dev, mode);
>  }
>  
> -- 
> 1.9.1
> 
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-- 
Ville Syrjälä
Intel OTC