[Intel-gfx] [PATCH v3 02/11] drm/i915: DisplayPort pixel clock check

[Ville Syrjälä]

On Fri, Jul 31, 2015 at 03:13:51PM +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 DisplayPort.
> 
> V2:
> - removed computation for max DOT clock
> 
> V3:
> - cleanup by removing unnecessary lines
> 
> Signed-off-by: Mika Kahola <mika.kahola at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_dp.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index 44f8a32..5faeadb 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -206,6 +206,7 @@ intel_dp_mode_valid(struct drm_connector *connector,
>  	struct drm_display_mode *fixed_mode = intel_connector->panel.fixed_mode;
>  	int target_clock = mode->clock;
>  	int max_rate, mode_rate, max_lanes, max_link_clock;
> +	int max_pixclk = to_i915(connector->dev)->max_dotclk;
>  
>  	if (is_edp(intel_dp) && fixed_mode) {
>  		if (mode->hdisplay > fixed_mode->hdisplay)
> @@ -223,7 +224,7 @@ intel_dp_mode_valid(struct drm_connector *connector,
>  	max_rate = intel_dp_max_data_rate(max_link_clock, max_lanes);
>  	mode_rate = intel_dp_link_required(target_clock, 18);
>  
> -	if (mode_rate > max_rate)
> +	if (mode_rate > max_rate || target_clock > max_pixclk)
>  		return MODE_CLOCK_HIGH;

This one ends up checking the fixed_mode clock every time, but I think I
already declared that to OK, so let's go with it.

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


>  	if (mode->clock < 10000)
> -- 
> 1.9.1
> 
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-- 
Ville Syrjälä
Intel OTC