[Intel-gfx] [PATCH] drm/i915: Print a debug message when exceeding dotclock limit on pre-gen4

[Ville Syrjälä]

On Wed, Nov 04, 2015 at 05:41:16PM +0200, Ander Conselvan De Oliveira wrote:
> Reviewed-by: Ander Conselvan de Oliveira <conselvan2 at gmail.com>

Pushed to dinq. Thanks for the review.

> On Fri, 2015-10-30 at 23:39 +0200, ville.syrjala at linux.intel.com wrote:
> > From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > 
> > Currently there's no trace in dmesg when the gen2/3 dotclock checks
> > reject the modeset. Add some to avoid further head scratching.
> > 
> > While at it refactor the code a bit to look nicer.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/intel_display.c | 26 ++++++++++++++++++--------
> >  1 file changed, 18 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/intel_display.c
> > b/drivers/gpu/drm/i915/intel_display.c
> > index 2b70151..1509a99 100644
> > --- a/drivers/gpu/drm/i915/intel_display.c
> > +++ b/drivers/gpu/drm/i915/intel_display.c
> > @@ -6599,6 +6599,15 @@ static void hsw_compute_ips_config(struct intel_crtc
> > *crtc,
> >  		pipe_config_supports_ips(dev_priv, pipe_config);
> >  }
> >  
> > +static bool intel_crtc_supports_double_wide(const struct intel_crtc *crtc)
> > +{
> > +	const struct drm_i915_private *dev_priv = to_i915(crtc->base.dev);
> > +
> > +	/* GDG double wide on either pipe, otherwise pipe A only */
> > +	return INTEL_INFO(dev_priv)->gen < 4 &&
> > +		(crtc->pipe == PIPE_A || IS_I915G(dev_priv));
> > +}
> > +
> >  static int intel_crtc_compute_config(struct intel_crtc *crtc,
> >  				     struct intel_crtc_state *pipe_config)
> >  {
> > @@ -6608,23 +6617,24 @@ static int intel_crtc_compute_config(struct intel_crtc
> > *crtc,
> >  
> >  	/* FIXME should check pixel clock limits on all platforms */
> >  	if (INTEL_INFO(dev)->gen < 4) {
> > -		int clock_limit = dev_priv->max_cdclk_freq;
> > +		int clock_limit = dev_priv->max_cdclk_freq * 9 / 10;
> >  
> >  		/*
> > -		 * Enable pixel doubling when the dot clock
> > +		 * Enable double wide mode when the dot clock
> >  		 * is > 90% of the (display) core speed.
> > -		 *
> > -		 * GDG double wide on either pipe,
> > -		 * otherwise pipe A only.
> >  		 */
> > -		if ((crtc->pipe == PIPE_A || IS_I915G(dev)) &&
> > -		    adjusted_mode->crtc_clock > clock_limit * 9 / 10) {
> > +		if (intel_crtc_supports_double_wide(crtc) &&
> > +		    adjusted_mode->crtc_clock > clock_limit) {
> >  			clock_limit *= 2;
> >  			pipe_config->double_wide = true;
> >  		}
> >  
> > -		if (adjusted_mode->crtc_clock > clock_limit * 9 / 10)
> > +		if (adjusted_mode->crtc_clock > clock_limit) {
> > +			DRM_DEBUG_KMS("requested pixel clock (%d kHz) too
> > high (max: %d kHz, double wide: %s)\n",
> > +				      adjusted_mode->crtc_clock, clock_limit,
> > +				      yesno(pipe_config->double_wide));
> >  			return -EINVAL;
> > +		}
> >  	}
> >  
> >  	/*

-- 
Ville Syrjälä
Intel OTC