Re: [PATCH 2/3] drm/i915/tgl: Read SAGV block time from PCODE

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

On Wed, Sep 25, 2019 at 01:33:51PM -0700, James Ausmus wrote:
> Starting from TGL, we now need to read the SAGV block time via a PCODE
> mailbox, rather than having a static value.
> 
> BSpec: 49326
> 
> Cc: Ville Syrjälä <ville.syrjala@intel.com>
> Cc: Stanislav Lisovskiy <stanislav.lisovskiy@intel.com>
> Cc: Lucas De Marchi <lucas.demarchi@intel.com>
> Signed-off-by: James Ausmus <james.ausmus@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_reg.h |  1 +
>  drivers/gpu/drm/i915/intel_pm.c | 20 +++++++++++++++-----
>  2 files changed, 16 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index e752de9470bd..84ae6553485b 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -8865,6 +8865,7 @@ enum {
>  #define     GEN9_SAGV_DISABLE			0x0
>  #define     GEN9_SAGV_IS_DISABLED		0x1
>  #define     GEN9_SAGV_ENABLE			0x3
> +#define GEN12_PCODE_READ_SAGV_BLOCK_TIME_US	0x23
>  #define GEN6_PCODE_DATA				_MMIO(0x138128)
>  #define   GEN6_PCODE_FREQ_IA_RATIO_SHIFT	8
>  #define   GEN6_PCODE_FREQ_RING_RATIO_SHIFT	16
> diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
> index 5ad72dcb0faa..ca2bec09edb5 100644
> --- a/drivers/gpu/drm/i915/intel_pm.c
> +++ b/drivers/gpu/drm/i915/intel_pm.c
> @@ -3665,16 +3665,26 @@ intel_has_sagv(struct drm_i915_private *dev_priv)
>  static int
>  intel_get_sagv_block_time_us(struct drm_i915_private *dev_priv)
>  {
> -	int sagv_block_time_us = 1000; /* Default to unusable block time */
> +	uint val = 0;

uint?

> +	int ret, sagv_block_time_us = 1000; /* Default to unusable block time */

val+ret could live in a tighter scope.

>  
> -	if (IS_GEN(dev_priv, 11))
> +	if (INTEL_GEN(dev_priv) >= 12) {
> +		ret = sandybridge_pcode_read(dev_priv,
> +					     GEN12_PCODE_READ_SAGV_BLOCK_TIME_US,
> +					     &val, NULL);

We should probably stash this somewhere so we don't have to keep
asking pcode about it every single time.

Magic numbers look correct
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

> +		if (!ret)
> +			sagv_block_time_us = val;
> +		else
> +			DRM_DEBUG_DRIVER("Couldn't read SAGV block time!\n");
> +	} else if (IS_GEN(dev_priv, 11)) {
>  		sagv_block_time_us = 10;
> -	else if (IS_GEN(dev_priv, 10))
> +	} else if (IS_GEN(dev_priv, 10)) {
>  		sagv_block_time_us = 20;
> -	else if (IS_GEN(dev_priv, 9))
> +	} else if (IS_GEN(dev_priv, 9)) {
>  		sagv_block_time_us = 30;
> -	else
> +	} else {
>  		MISSING_CASE(INTEL_GEN(dev_priv));
> +	}
>  
>  	return sagv_block_time_us;
>  }
> -- 
> 2.22.1
> 
> _______________________________________________
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> Intel-gfx@lists.freedesktop.org
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-- 
Ville Syrjälä
Intel
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