[Intel-gfx] [PATCH 01/12] drm/i915: Grab the pixel clock from adjusted_mode not requested_mode

[Ville Syrjälä]

On Mon, Sep 02, 2013 at 08:38:16PM +0200, Daniel Vetter wrote:
> On Mon, Sep 02, 2013 at 09:13:28PM +0300, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > intel_crtc_compute_config() and i9xx_set_pipeconf() attempt to get
> > the current pixel clock from requested_mode. requested_mode.clock may
> > be totally bogus, so the clock should come from adjusted_mode.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 5 ++---
> >  1 file changed, 2 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> > index ecb8b52..cab1319 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -4124,8 +4124,7 @@ static int intel_crtc_compute_config(struct intel_crtc *crtc,
> >  
> >  	if (HAS_PCH_SPLIT(dev)) {
> >  		/* FDI link clock is fixed at 2.7G */
> > -		if (pipe_config->requested_mode.clock * 3
> > -		    > IRONLAKE_FDI_FREQ * 4)
> > +		if (adjusted_mode->clock * 3 > IRONLAKE_FDI_FREQ * 4)
> 
> Note quite: The fdi dotclock is the adjusted mode's clock but with the
> pixel multiplier _not_ taken into account. See
> ironlake_fdi_compute_config. Maybe we need a fdi_dotclock_from_pipe_config
> helper function?

Dang those pixel multipliers. I need to study on the topic a bit more.
I'm confused whether the pipe is actually pushing out pixels at the
non-multiplied rate or the multiplied rate. That's an important detail
when we consider the CDCLK vs. pipe pixel rate limitations.

-- 
Ville Syrjälä
Intel OTC