Re: [PATCH 2/4] drm/i915/bxt: Determine BXT slice/subslice/EU info

Imre Deak
2015-04-09T13:26:21Z

On Fri, 2015-04-03 at 18:13 -0700, jeff.mcgee@intel.com wrote:
> From: Jeff McGee <jeff.mcgee@intel.com>
>
> Modify the Gen9 SSEU info initialization logic to support
> Broxton. Broxton reuses the SKL fuse registers but has at most
> 1 slice and 6 EU per subslice.
>
> Signed-off-by: Jeff McGee <jeff.mcgee@intel.com>
> ---
> drivers/gpu/drm/i915/i915_dma.c | 47 ++++++++++++++++++++++++++---------------
> drivers/gpu/drm/i915/i915_reg.h | 4 +---
> 2 files changed, 31 insertions(+), 20 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index 9691f0f..a9b7770 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -611,9 +611,21 @@ static void gen9_sseu_info_init(struct drm_device *dev)
> {
> struct drm_i915_private *dev_priv = dev->dev_private;
> struct intel_device_info *info;
> - const int s_max = 3, ss_max = 4, eu_max = 8;
> + int s_max = 3, ss_max = 4, eu_max = 8;
> int s, ss;
> - u32 fuse2, eu_disable[s_max], s_enable, ss_disable;
> + u32 fuse2, s_enable, ss_disable, eu_disable;
> + u8 eu_mask = 0xff;
> +
> + /*
> + * BXT has a single slice. BXT also has at most 6 EU per subslice,
> + * and therefore only the lowest 6 bits of the 8-bit EU disable
> + * fields are valid.
> + */
> + if (IS_BROXTON(dev)) {
> + s_max = 1;
> + eu_max = 6;
> + eu_mask = 0x3f;
> + }
>
> info = (struct intel_device_info *)&dev_priv->info;
> fuse2 = I915_READ(GEN8_FUSE2);
> @@ -622,10 +634,6 @@ static void gen9_sseu_info_init(struct drm_device *dev)
> ss_disable = (fuse2 & GEN9_F2_SS_DIS_MASK) >>
> GEN9_F2_SS_DIS_SHIFT;
>
> - eu_disable[0] = I915_READ(GEN8_EU_DISABLE0);
> - eu_disable[1] = I915_READ(GEN8_EU_DISABLE1);
> - eu_disable[2] = I915_READ(GEN8_EU_DISABLE2);
> -
> info->slice_total = hweight32(s_enable);
> /*
> * The subslice disable field is global, i.e. it applies
> @@ -644,25 +652,26 @@ static void gen9_sseu_info_init(struct drm_device *dev)
> /* skip disabled slice */
> continue;
>
> + eu_disable = I915_READ(GEN9_EU_DISABLE(s));
> for (ss = 0; ss < ss_max; ss++) {
> - u32 n_disabled;
> + int eu_per_ss;
>
> if (ss_disable & (0x1 << ss))
> /* skip disabled subslice */
> continue;
>
> - n_disabled = hweight8(eu_disable[s] >>
> - (ss * eu_max));
> + eu_per_ss = eu_max - hweight8((eu_disable >> (ss*8)) &
> + eu_mask);
>
> /*
> * Record which subslice(s) has(have) 7 EUs. we
> * can tune the hash used to spread work among
> * subslices if they are unbalanced.
> */
> - if (eu_max - n_disabled == 7)
> + if (eu_per_ss == 7)
> info->subslice_7eu[s] |= 1 << ss;
>
> - info->eu_total += eu_max - n_disabled;
> + info->eu_total += eu_per_ss;
> }
> }
>
> @@ -670,7 +679,8 @@ static void gen9_sseu_info_init(struct drm_device *dev)
> * SKL is expected to always have a uniform distribution
> * of EU across subslices with the exception that any one
> * EU in any one subslice may be fused off for die
> - * recovery.
> + * recovery. BXT is expected to be perfectly uniform in EU
> + * distribution.

Nitpick: I would have added here an assertion for BXT about the above.
The patchset looks otherwise ok to me, so on 1-4:
Reviewed-by: Imre Deak <imre.deak@intel.com>

> */
> info->eu_per_subslice = info->subslice_total ?
> DIV_ROUND_UP(info->eu_total,
> @@ -678,11 +688,14 @@ static void gen9_sseu_info_init(struct drm_device *dev)
> /*
> * SKL supports slice power gating on devices with more than
> * one slice, and supports EU power gating on devices with
> - * more than one EU pair per subslice.
> + * more than one EU pair per subslice. BXT 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 = (info->slice_total > 1) ? 1 : 0;
> - info->has_subslice_pg = 0;
> - info->has_eu_pg = (info->eu_per_subslice > 2) ? 1 : 0;
> + info->has_slice_pg = (IS_SKYLAKE(dev) && (info->slice_total > 1));
> + info->has_subslice_pg = (IS_BROXTON(dev) && (info->subslice_total > 1));
> + info->has_eu_pg = (info->eu_per_subslice > 2);
> }
>
> /*
> @@ -747,7 +760,7 @@ static void intel_device_info_runtime_init(struct drm_device *dev)
> /* Initialize slice/subslice/EU info */
> if (IS_CHERRYVIEW(dev))
> cherryview_sseu_info_init(dev);
> - else if (IS_SKYLAKE(dev))
> + else if (INTEL_INFO(dev)->gen >= 9)
> gen9_sseu_info_init(dev);
>
> DRM_DEBUG_DRIVER("slice total: %u\n", info->slice_total);
> diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
> index b134fa3..69d3689 100644
> --- a/drivers/gpu/drm/i915/i915_reg.h
> +++ b/drivers/gpu/drm/i915/i915_reg.h
> @@ -1554,9 +1554,7 @@ enum skl_disp_power_wells {
> #define GEN9_F2_SS_DIS_SHIFT 20
> #define GEN9_F2_SS_DIS_MASK (0xf << GEN9_F2_SS_DIS_SHIFT)
>
> -#define GEN8_EU_DISABLE0 0x9134
> -#define GEN8_EU_DISABLE1 0x9138
> -#define GEN8_EU_DISABLE2 0x913c
> +#define GEN9_EU_DISABLE(slice) (0x9134 + (slice)*0x4)
>
> #define GEN6_BSD_SLEEP_PSMI_CONTROL 0x12050
> #define GEN6_BSD_SLEEP_MSG_DISABLE (1 << 0)