Re: [PATCH v3] drm/i915: Setup static bias for GPU

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

On Wed, Apr 29, 2015 at 08:36:24AM +0530, deepak.s@linux.intel.com wrote:
> From: Deepak S <deepak.s@linux.intel.com>
> 
> Based on the spec, Setting up static BIAS for GPU to improve the
> rps performace.
> 
> v2: rename reg defn to match spec. (Ville)
> 
> v3: Updated bias setting for chv (Deepak)
> 
> Signed-off-by: Deepak S <deepak.s@linux.intel.com>

Matches the spec. Whether the chosen bias is really the best, I can't
really say. But favoring the GPU does seem like a sensible idea if we
want to keep the UI stuff fluid enough while there's some CPU heavy
tasks running at the same time.

Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> ---
>  drivers/gpu/drm/i915/i915_reg.h |  6 ++++++
>  drivers/gpu/drm/i915/intel_pm.c | 12 ++++++++++++
>  2 files changed, 18 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 36805b6..048987e 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -670,6 +670,12 @@ enum skl_disp_power_wells {
>  #define   FB_FMAX_VMIN_FREQ_LO_SHIFT		27
>  #define   FB_FMAX_VMIN_FREQ_LO_MASK		0xf8000000
>  
> +#define VLV_TURBO_SOC_OVERRIDE	0x04
> +#define 	VLV_OVERRIDE_EN	1
> +#define 	VLV_SOC_TDP_EN	(1 << 1)
> +#define 	VLV_BIAS_CPU_125_SOC_875 (6 << 2)
> +#define 	CHV_BIAS_CPU_50_SOC_50 (3 << 2)
> +
>  #define VLV_CZ_CLOCK_TO_MILLI_SEC		100000
>  
>  /* vlv2 north clock has */
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 78c89ff..3689d0e 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -5065,6 +5065,12 @@ static void cherryview_enable_rps(struct drm_device *dev)
>  		   GEN6_RP_UP_BUSY_AVG |
>  		   GEN6_RP_DOWN_IDLE_AVG);
>  
> +	/* Setting Fixed Bias */
> +	val = VLV_OVERRIDE_EN |
> +		  VLV_SOC_TDP_EN |
> +		  CHV_BIAS_CPU_50_SOC_50;
> +	vlv_punit_write(dev_priv, VLV_TURBO_SOC_OVERRIDE, val);
> +
>  	val = vlv_punit_read(dev_priv, PUNIT_REG_GPU_FREQ_STS);
>  
>  	/* RPS code assumes GPLL is used */
> @@ -5149,6 +5155,12 @@ static void valleyview_enable_rps(struct drm_device *dev)
>  
>  	I915_WRITE(GEN6_RC_CONTROL, rc6_mode);
>  
> +	/* Setting Fixed Bias */
> +	val = VLV_OVERRIDE_EN |
> +		  VLV_SOC_TDP_EN |
> +		  VLV_BIAS_CPU_125_SOC_875;
> +	vlv_punit_write(dev_priv, VLV_TURBO_SOC_OVERRIDE, val);
> +
>  	val = vlv_punit_read(dev_priv, PUNIT_REG_GPU_FREQ_STS);
>  
>  	/* RPS code assumes GPLL is used */
> -- 
> 1.9.1

-- 
Ville Syrjälä
Intel OTC
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