Re: [PATCH v3 08/11] drm/i915: TV pixel clock check

[Daniel Vetter <daniel@ffwll.ch>]

On Wed, Aug 12, 2015 at 09:24:01PM +0300, Ville Syrjälä wrote:
> On Fri, Jul 31, 2015 at 03:13:57PM +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 TV.
> > 
> > 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_tv.c | 4 ++++
> >  1 file changed, 4 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_tv.c b/drivers/gpu/drm/i915/intel_tv.c
> > index 8b9d325..beeed25 100644
> > --- a/drivers/gpu/drm/i915/intel_tv.c
> > +++ b/drivers/gpu/drm/i915/intel_tv.c
> > @@ -897,6 +897,10 @@ intel_tv_mode_valid(struct drm_connector *connector,
> >  {
> >  	struct intel_tv *intel_tv = intel_attached_tv(connector);
> >  	const struct tv_mode *tv_mode = intel_tv_mode_find(intel_tv);
> > +	int max_pixclk = to_i915(connector->dev)->max_dotclk;
> > +
> > +	if (mode->clock > max_pixclk)
> > +		return MODE_CLOCK_HIGH;
> 
> The mode handling in intel_tv.c seems to be a mess. But I suppose this
> should be OK.

We set a fake mode (which is the one userspace asks for) and the hw
internally munges it to the actual tv mode with a scaler. Except that the
frame-start/dotclock are fed from the actual TV mode (which is why
kms_flip has a check for TV modes since the timings are all wrong).

Yup, giant hairball indeed ;-)
-Daniel

> 
> Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> >  
> >  	/* Ensure TV refresh is close to desired refresh */
> >  	if (tv_mode && abs(tv_mode->refresh - drm_mode_vrefresh(mode) * 1000)
> > -- 
> > 1.9.1
> > 
> > _______________________________________________
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> 
> -- 
> Ville Syrjälä
> Intel OTC
> _______________________________________________
> Intel-gfx mailing list
> Intel-gfx@lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/intel-gfx

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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