[Intel-gfx] [PATCH 3/9] drm/i915: Check pixel clock when setting mode for LVDS

[Chris Wilson]

On Fri, Jul 03, 2015 at 02:35:51PM +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 LVDS.
> 
> Signed-off-by: Mika Kahola <mika.kahola at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_lvds.c | 18 ++++++++++++++++++
>  1 file changed, 18 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_lvds.c b/drivers/gpu/drm/i915/intel_lvds.c
> index ea85547..3280413 100644
> --- a/drivers/gpu/drm/i915/intel_lvds.c
> +++ b/drivers/gpu/drm/i915/intel_lvds.c
> @@ -262,13 +262,31 @@ static void intel_disable_lvds(struct intel_encoder *encoder)
>  	POSTING_READ(lvds_encoder->reg);
>  }
>  
> +static int
> +intel_lvds_max_pixclk(struct drm_connector *connector)
> +{
> +	struct drm_i915_private *dev_priv = to_i915(connector->dev);
> +
> +	if (IS_CHERRYVIEW(connector->dev))
> +		return  DIV_ROUND_UP(dev_priv->max_cdclk_freq * 100, 95);
> +	else if (IS_VALLEYVIEW(connector->dev))
> +		return  DIV_ROUND_UP(dev_priv->max_cdclk_freq * 100, 90);
> +	else
> +		return dev_priv->max_cdclk_freq;
> +}
> +
>  static enum drm_mode_status
>  intel_lvds_mode_valid(struct drm_connector *connector,
>  		      struct drm_display_mode *mode)
>  {
>  	struct intel_connector *intel_connector = to_intel_connector(connector);
>  	struct drm_display_mode *fixed_mode = intel_connector->panel.fixed_mode;
> +	int max_pixclk;
> +
> +	max_pixclk = intel_lvds_max_pixclk(connector);
>  
> +	if (mode->clock > max_pixclk)
> +		return MODE_PANEL;

return MODE_CLOCK_HIGH;
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre