Re: [PATCH v3 01/11] drm/i915: Store max dotclock

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Fri, Jul 31, 2015 at 03:13:50PM +0300, Mika Kahola wrote:
> Store max dotclock into dev_priv structure so we are able
> to filter out the modes that are not supported by our
> platforms.
> 
> V2:
> - limit the max dot clock frequency to max CD clock frequency
>   for the gen9 and above
> - limit the max dot clock frequency to 90% of the max CD clock
>   frequency for the older gens
> - for Cherryview the max dot clock frequency is limited to 95%
>   of the max CD clock frequency
> - for gen2 and gen3 the max dot clock limit is set to 90% of the
>   2X max CD clock frequency
> 
> Signed-off-by: Mika Kahola <mika.kahola@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_drv.h      |  1 +
>  drivers/gpu/drm/i915/intel_display.c | 19 +++++++++++++++++++
>  2 files changed, 20 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 04aa34a..1f69211b 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -1777,6 +1777,7 @@ struct drm_i915_private {
>  	unsigned int fsb_freq, mem_freq, is_ddr3;
>  	unsigned int skl_boot_cdclk;
>  	unsigned int cdclk_freq, max_cdclk_freq;
> +	unsigned int max_dotclk;

nit: maybe max_dotclk_freq for extra consistentcy?

>  	unsigned int hpll_freq;
>  
>  	/**
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 43b0f17..c9c6d19 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -5259,6 +5259,23 @@ static void modeset_update_crtc_power_domains(struct drm_atomic_state *state)
>  			modeset_put_power_domains(dev_priv, put_domains[i]);
>  }
>  
> +static int intel_compute_max_dotclk(struct drm_i915_private *dev_priv)
> +{
> +	int max_cdclk_freq = dev_priv->max_cdclk_freq;
> +	int max_dotclk_freq;
> +
> +	if (INTEL_INFO(dev_priv)->gen >= 9)
> +		max_dotclk_freq = max_cdclk_freq;
> +	else if (IS_CHERRYVIEW(dev_priv))
> +		max_dotclk_freq = DIV_ROUND_UP(max_cdclk_freq * 95, 100);
> +	else if (INTEL_INFO(dev_priv)->gen == 2 || INTEL_INFO(dev_priv)->gen == 3)

intel_crtc_compute_config() uses 'gen < 4' as the condition around the
double_wide handling. Maybe do the same here for consistency.

> +		max_dotclk_freq = DIV_ROUND_UP(2 * max_cdclk_freq * 90, 100);
> +	else
> +		max_dotclk_freq = DIV_ROUND_UP(max_cdclk_freq * 90, 100);

These should round down to match what we do in the calc_cdclk funcs.

Also to add another bikeshed color, there's no need for the local
max_dotclk_freq variable, you can just 'return <whatever>' from each
branch.

With at least the rounding fixed this can have
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +
> +	return max_dotclk_freq;
> +}
> +
>  static void intel_update_max_cdclk(struct drm_device *dev)
>  {
>  	struct drm_i915_private *dev_priv = dev->dev_private;
> @@ -5298,6 +5315,8 @@ static void intel_update_max_cdclk(struct drm_device *dev)
>  		dev_priv->max_cdclk_freq = dev_priv->cdclk_freq;
>  	}
>  
> +	dev_priv->max_dotclk = intel_compute_max_dotclk(dev_priv);
> +
>  	DRM_DEBUG_DRIVER("Max CD clock rate: %d kHz\n",
>  			 dev_priv->max_cdclk_freq);
>  }
> -- 
> 1.9.1
> 
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-- 
Ville Syrjälä
Intel OTC
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