Re: [PATCH v3 05/11] drm/i915: SDVO pixel clock check

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Jul 31, 2015 at 03:13:54PM +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 SDVO.
> 
> V2:
> - removed computation for max pixel clock
> 
> V3:
> - cleanup by removing unnecessary lines
> 
> Signed-off-by: Mika Kahola <mika.kahola@intel.com>
> ---
>  drivers/gpu/drm/i915/intel_sdvo.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_sdvo.c b/drivers/gpu/drm/i915/intel_sdvo.c
> index 2c435a7..55a2853 100644
> --- a/drivers/gpu/drm/i915/intel_sdvo.c
> +++ b/drivers/gpu/drm/i915/intel_sdvo.c
> @@ -1560,6 +1560,7 @@ intel_sdvo_mode_valid(struct drm_connector *connector,
>  		      struct drm_display_mode *mode)
>  {
>  	struct intel_sdvo *intel_sdvo = intel_attached_sdvo(connector);
> +	int max_pixclk = to_i915(connector->dev)->max_dotclk;
>  
>  	if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
>  		return MODE_NO_DBLESCAN;
> @@ -1570,6 +1571,9 @@ intel_sdvo_mode_valid(struct drm_connector *connector,
>  	if (intel_sdvo->pixel_clock_max < mode->clock)
>  		return MODE_CLOCK_HIGH;
>  
> +	if (mode->clock > max_pixclk)
> +		return MODE_CLOCK_HIGH;
> +

Had to think a bit on this one. But yeah checking mode->clock is the
right thing. I suppose in theory we should do the whole
intel_sdvo_get_preferred_input_mode() thing here, but I guess that would
clobber the current sdvo device state and so can't be done safely.

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

>  	if (intel_sdvo->is_lvds) {
>  		if (mode->hdisplay > intel_sdvo->sdvo_lvds_fixed_mode->hdisplay)
>  			return MODE_PANEL;
> -- 
> 1.9.1
> 
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-- 
Ville Syrjälä
Intel OTC
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