Re: [PATCH 1/2] drm/i915/chv: Determine CHV slice/subslice/EU info

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: jeff.mcgee@intel.com
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH 1/2] drm/i915/chv: Determine CHV slice/subslice/EU info
Date: Fri, 27 Feb 2015 20:29:13 +0200	[thread overview]
Message-ID: <20150227182913.GS11371@intel.com> (raw)
In-Reply-To: <1425061352-29188-2-git-send-email-jeff.mcgee@intel.com>

On Fri, Feb 27, 2015 at 10:22:31AM -0800, jeff.mcgee@intel.com wrote:
> From: Jeff McGee <jeff.mcgee@intel.com>
> 
> Total EU was already being detected on CHV, so we just add the
> additional info parameters. The detection method is changed to
> be more robust in the case of subslice fusing - we don't want
> to trust the EU fuse bits corresponding to subslices which are
> fused-off.
> 
> Signed-off-by: Jeff McGee <jeff.mcgee@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_dma.c | 40 ++++++++++++++++++++++++++++++++++------
>  drivers/gpu/drm/i915/i915_reg.h |  2 ++
>  2 files changed, 36 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 053e178..04e5b55e 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -608,14 +608,42 @@ static void intel_device_info_runtime_init(struct drm_device *dev)
>  
>  	/* Initialize slice/subslice/EU info */
>  	if (IS_CHERRYVIEW(dev)) {
> -		u32 fuse, mask_eu;
> +		u32 fuse, eu_dis;
>  
>  		fuse = I915_READ(CHV_FUSE_GT);
> -		mask_eu = fuse & (CHV_FGT_EU_DIS_SS0_R0_MASK |
> -				  CHV_FGT_EU_DIS_SS0_R1_MASK |
> -				  CHV_FGT_EU_DIS_SS1_R0_MASK |
> -				  CHV_FGT_EU_DIS_SS1_R1_MASK);
> -		info->eu_total = 16 - hweight32(mask_eu);
> +
> +		info->slice_total = 1;
> +
> +		if (!(fuse & CHV_FGT_DISABLE_SS0)) {
                             ^^^^^^^^^^^^^^^^^^^

That's your shift value. Masking with it probably won't work :P

> +			info->subslice_per_slice++;
> +			eu_dis = fuse & (CHV_FGT_EU_DIS_SS0_R0_MASK |
> +					 CHV_FGT_EU_DIS_SS0_R1_MASK);
> +			info->eu_total += 8 - hweight32(eu_dis);
> +		}
> +
> +		if (!(fuse & CHV_FGT_DISABLE_SS1)) {

ditto

> +			info->subslice_per_slice++;
> +			eu_dis = fuse & (CHV_FGT_EU_DIS_SS1_R0_MASK |
> +					CHV_FGT_EU_DIS_SS1_R1_MASK);
> +			info->eu_total += 8 - hweight32(eu_dis);
> +		}
> +
> +		info->subslice_total = info->subslice_per_slice;
> +		/*
> +		 * CHV expected to always have a uniform distribution of EU
> +		 * across subslices.
> +		*/
> +		info->eu_per_subslice = info->subslice_total ?
> +					info->eu_total / info->subslice_total :
> +					0;
> +		/*
> +		 * CHV supports subslice power gating on devices with more than
> +		 * one subslice, and supports EU power gating on devices with
> +		 * more than one EU pair per subslice.
> +		*/
> +		info->has_slice_pg = 0;
> +		info->has_subslice_pg = (info->subslice_total > 1) ? 1 : 0;
> +		info->has_eu_pg = (info->eu_per_subslice > 2) ? 1 : 0;

Nit: use of ?: seems pointless in these.

>  	} else if (IS_SKYLAKE(dev)) {
>  		const int s_max = 3, ss_max = 4, eu_max = 8;
>  		int s, ss;
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index 55143cb..a8b205d 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -1522,6 +1522,8 @@ enum skl_disp_power_wells {
>  
>  /* Fuse readout registers for GT */
>  #define CHV_FUSE_GT			(VLV_DISPLAY_BASE + 0x2168)
> +#define   CHV_FGT_DISABLE_SS0		10
> +#define   CHV_FGT_DISABLE_SS1		11
>  #define   CHV_FGT_EU_DIS_SS0_R0_SHIFT	16
>  #define   CHV_FGT_EU_DIS_SS0_R0_MASK	(0xf << CHV_FGT_EU_DIS_SS0_R0_SHIFT)
>  #define   CHV_FGT_EU_DIS_SS0_R1_SHIFT	20
> -- 
> 2.3.0

-- 
Ville Syrjälä
Intel OTC
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