[Intel-gfx] [PATCH 3/3] drm/i915: Fix comments about GMBUSFREQ register

Mika Kahola mika.kahola at intel.com
Wed Apr 27 13:30:14 UTC 2016


s/Programmng/Programming

With this nitpick fixed, this is

Reviewed-by: Mika Kahola <mika.kahola at intel.com>

On Tue, 2016-04-26 at 19:46 +0300, ville.syrjala at linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala at linux.intel.com>
> 
> The comment about GMBUSFREQ is confused. The spec actually explains
> the 4MHz thing perfectly by noting that the 4MHz divider values is
> actually just bits [9:2] not [9:0], hence the divide by 1000 correct.
> Replace the confused note with a quote from the spec, and eliminate
> the duplicated comment that snuck in.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
> ---
>  drivers/gpu/drm/i915/intel_display.c | 15 +++++----------
>  1 file changed, 5 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index ea55dd331fac..ec9144ded255 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -5311,18 +5311,13 @@ static void intel_update_cdclk(struct drm_device *dev)
>  			 dev_priv->cdclk_freq);
>  
>  	/*
> -	 * Program the gmbus_freq based on the cdclk frequency.
> -	 * BSpec erroneously claims we should aim for 4MHz, but
> -	 * in fact 1MHz is the correct frequency.
> +	 * 9:0 CMBUS [sic] CDCLK frequency (cdfreq):
> +	 * Programmng [sic] note: bit[9:2] should be programmed to the number
> +	 * of cdclk that generates 4MHz reference clock freq which is used to
> +	 * generate GMBus clock. This will vary with the cdclk freq.
>  	 */
> -	if (IS_VALLEYVIEW(dev) || IS_CHERRYVIEW(dev)) {
> -		/*
> -		 * Program the gmbus_freq based on the cdclk frequency.
> -		 * BSpec erroneously claims we should aim for 4MHz, but
> -		 * in fact 1MHz is the correct frequency.
> -		 */
> +	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv))
>  		I915_WRITE(GMBUSFREQ_VLV, DIV_ROUND_UP(dev_priv->cdclk_freq, 1000));
> -	}
>  
>  	if (dev_priv->max_cdclk_freq == 0)
>  		intel_update_max_cdclk(dev);

-- 
Mika Kahola - Intel OTC



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