[Intel-gfx] [PATCH v3 03/11] drm/i915: HDMI pixel clock check

[Ville Syrjälä]

On Fri, Jul 31, 2015 at 03:13:52PM +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 HDMI.
> 
> 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_hdmi.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
> index 70bad5b..3149e5f 100644
> --- a/drivers/gpu/drm/i915/intel_hdmi.c
> +++ b/drivers/gpu/drm/i915/intel_hdmi.c
> @@ -1193,10 +1193,14 @@ intel_hdmi_mode_valid(struct drm_connector *connector,
>  	struct drm_device *dev = intel_hdmi_to_dev(hdmi);
>  	enum drm_mode_status status;
>  	int clock;
> +	int max_pixclk = to_i915(connector->dev)->max_dotclk;
>  
>  	if (mode->flags & DRM_MODE_FLAG_DBLSCAN)
>  		return MODE_NO_DBLESCAN;
>  
> +	if (mode->clock > max_pixclk)
> +		return MODE_CLOCK_HIGH;
> +
>  	clock = mode->clock;

I believe we should do something like this here:

	clock = mode->clock;

	if ((mode->flags & DRM_MODE_FLAG_3D_MASK) == DRM_MODE_FLAG_3D_FRAME_PACKING)
		clock *= 2;

	if (clock > max_pixclk)
		return MODE_CLOCK_HIGH;

>  	if (mode->flags & DRM_MODE_FLAG_DBLCLK)
>  		clock *= 2;

The stero handling should probably be in a separate patch, but in
preparation for it you could already put the dotclk check between the
clock= assigment and the DBCLK doubling (since DBLCLK only affects the
port_clock and not pixel clock).

> -- 
> 1.9.1
> 
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Ville Syrjälä
Intel OTC