Re: [PATCH 13/13] drm/i915: Eliminate the CDCLK_CTL RMW on BXT

[Imre Deak <imre.deak@intel.com>]

On Wed, 2016-05-11 at 22:44 +0300, ville.syrjala@linux.intel.com wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> 
> All the fields in CDCLK_CTL we don't program should be left at zero, so
> let's just get rid of the RMW.
> 
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Imre Deak <imre.deak@intel.com>

> ---
>  drivers/gpu/drm/i915/intel_display.c | 8 +-------
>  1 file changed, 1 insertion(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
> index 39990bfe47f2..3b6b9de968c5 100644
> --- a/drivers/gpu/drm/i915/intel_display.c
> +++ b/drivers/gpu/drm/i915/intel_display.c
> @@ -5433,24 +5433,18 @@ static void broxton_set_cdclk(struct drm_i915_private *dev_priv, int cdclk)
>  		if (wait_for(I915_READ(BXT_DE_PLL_ENABLE) & BXT_DE_PLL_LOCK, 1))
>  			DRM_ERROR("timeout waiting for DE PLL lock\n");
>  
> -		val = I915_READ(CDCLK_CTL);
> +		val = divider | skl_cdclk_decimal(cdclk);
>  		/*
>  		 * FIXME if only the cd2x divider needs changing, it could be done
>  		 * without shutting off the pipe (if only one pipe is active).
>  		 */
>  		val |= BXT_CDCLK_CD2X_PIPE_NONE;
> -		val &= ~BXT_CDCLK_CD2X_DIV_SEL_MASK;
> -		val |= divider;
>  		/*
>  		 * Disable SSA Precharge when CD clock frequency < 500 MHz,
>  		 * enable otherwise.
>  		 */
> -		val &= ~BXT_CDCLK_SSA_PRECHARGE_ENABLE;
>  		if (cdclk >= 500000)
>  			val |= BXT_CDCLK_SSA_PRECHARGE_ENABLE;
> -
> -		val &= ~CDCLK_FREQ_DECIMAL_MASK;
> -		val |= skl_cdclk_decimal(cdclk);
>  		I915_WRITE(CDCLK_CTL, val);
>  	}
>  
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