Re: [PATCH 4/7] drm/i915: sseu: convert slice count field to mask

Ben Widawsky
2015-11-19T23:40:46Z

On Wed, Oct 21, 2015 at 06:40:34PM +0300, Imre Deak wrote:
> In an upcoming patch we'll need the actual mask of slices in addition to
> their count, so replace the count field with a mask.
>
> Signed-off-by: Imre Deak <imre.deak@intel.com>
> ---
> drivers/gpu/drm/i915/i915_debugfs.c | 14 +++++++-------
> drivers/gpu/drm/i915/i915_dma.c | 37 +++++++++++++++++++------------------
> drivers/gpu/drm/i915/i915_drv.h | 2 +-
> drivers/gpu/drm/i915/intel_lrc.c | 2 +-
> 4 files changed, 28 insertions(+), 27 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c
> index 183c1f2..390dc59 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -4965,7 +4965,7 @@ static void cherryview_sseu_device_status(struct drm_device *dev,
> /* skip disabled subslice */
> continue;
>
> - stat->slice_total = 1;
> + stat->slice_mask = BIT(0);
> stat->subslice_per_slice++;
> eu_cnt = ((sig1[ss] & CHV_EU08_PG_ENABLE) ? 0 : 2) +
> ((sig1[ss] & CHV_EU19_PG_ENABLE) ? 0 : 2) +
> @@ -5014,7 +5014,7 @@ static void gen9_sseu_device_status(struct drm_device *dev,
> /* skip disabled slice */
> continue;
>
> - stat->slice_total++;
> + stat->slice_mask |= BIT(s);
>
> if (IS_SKYLAKE(dev))
> ss_cnt = INTEL_INFO(dev)->sseu.subslice_per_slice;
> @@ -5052,18 +5052,18 @@ static void broadwell_sseu_device_status(struct drm_device *dev,
> int s;
> u32 slice_info = I915_READ(GEN8_GT_SLICE_INFO);
>
> - stat->slice_total = hweight32(slice_info & GEN8_LSLICESTAT_MASK);
> + stat->slice_mask = slice_info & GEN8_LSLICESTAT_MASK;
>
> - if (stat->slice_total) {
> + if (stat->slice_mask) {
> stat->subslice_per_slice =
> INTEL_INFO(dev)->sseu.subslice_per_slice;
> - stat->subslice_total = stat->slice_total *
> + stat->subslice_total = hweight32(stat->slice_mask) *
^ hweight8?

> stat->subslice_per_slice;
> stat->eu_per_subslice = INTEL_INFO(dev)->sseu.eu_per_subslice;
> stat->eu_total = stat->eu_per_subslice * stat->subslice_total;
>
> /* subtract fused off EU(s) from enabled slice(s) */
> - for (s = 0; s < stat->slice_total; s++) {
> + for (s = 0; s < hweight32(stat->slice_mask); s++) {
^ hweight8?

how about for_each_set_bit(s, stat->slice_mask, 8) {} ?

> u8 subslice_7eu = INTEL_INFO(dev)->sseu.subslice_7eu[s];
>
> stat->eu_total -= hweight8(subslice_7eu);
> @@ -5077,7 +5077,7 @@ static void i915_print_sseu_info(struct seq_file *m, bool is_available_info,
> const char *type = is_available_info ? "Available" : "Enabled";
>
> seq_printf(m, " %s Slice Total: %u\n", type,
> - sseu->slice_total);
> + hweight32(sseu->slice_mask));
^ hweight8?

> seq_printf(m, " %s Subslice Total: %u\n", type,
> sseu->subslice_total);
> seq_printf(m, " %s Subslice Per Slice: %u\n", type,
> diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
> index be8e141..1f5f3a7d 100644
> --- a/drivers/gpu/drm/i915/i915_dma.c
> +++ b/drivers/gpu/drm/i915/i915_dma.c
> @@ -559,7 +559,7 @@ static void cherryview_sseu_info_init(struct drm_device *dev)
> info = (struct sseu_dev_info *)&INTEL_INFO(dev_priv)->sseu;
> fuse = I915_READ(CHV_FUSE_GT);
>
> - info->slice_total = 1;
> + info->slice_mask = BIT(0);
>
> if (!(fuse & CHV_FGT_DISABLE_SS0)) {
> info->subslice_per_slice++;
> @@ -599,23 +599,21 @@ static void gen9_sseu_info_init(struct drm_device *dev)
> struct sseu_dev_info *info;
> int s_max = 3, ss_max = 4, eu_max = 8;
> int s, ss;
> - u32 fuse2, s_enable, ss_disable, eu_disable;
> + u32 fuse2, ss_disable, eu_disable;
> u8 eu_mask = 0xff;
>
> info = (struct sseu_dev_info *)&INTEL_INFO(dev_priv)->sseu;
> fuse2 = I915_READ(GEN8_FUSE2);
> - s_enable = (fuse2 & GEN8_F2_S_ENA_MASK) >>
> - GEN8_F2_S_ENA_SHIFT;
> + info->slice_mask = (fuse2 & GEN8_F2_S_ENA_MASK) >> GEN8_F2_S_ENA_SHIFT;
> ss_disable = (fuse2 & GEN9_F2_SS_DIS_MASK) >>
> GEN9_F2_SS_DIS_SHIFT;
>
> - info->slice_total = hweight32(s_enable);
> /*
> * The subslice disable field is global, i.e. it applies
> * to each of the enabled slices.
> */
> info->subslice_per_slice = ss_max - hweight32(ss_disable);
> - info->subslice_total = info->slice_total *
> + info->subslice_total = hweight32(info->slice_mask) *
^ hweight8?
> info->subslice_per_slice;
>
> /*
> @@ -623,7 +621,7 @@ static void gen9_sseu_info_init(struct drm_device *dev)
> * count the total enabled EU.
> */
> for (s = 0; s < s_max; s++) {
> - if (!(s_enable & (0x1 << s)))
> + if (!(info->slice_mask & BIT(s)))

You could do for_each_set_bit again here too if you like.

> /* skip disabled slice */
> continue;
>
> @@ -668,7 +666,8 @@ static void gen9_sseu_info_init(struct drm_device *dev)
> * supports EU power gating on devices with more than one EU
> * pair per subslice.
> */
> - info->has_slice_pg = (IS_SKYLAKE(dev) && (info->slice_total > 1));
> + info->has_slice_pg = IS_SKYLAKE(dev) &&
> + hweight32(info->slice_mask) > 1;
^ hweight8?

> info->has_subslice_pg = (IS_BROXTON(dev) && (info->subslice_total > 1));
> info->has_eu_pg = (info->eu_per_subslice > 2);
> }
> @@ -679,10 +678,14 @@ static void broadwell_sseu_info_init(struct drm_device *dev)
> struct sseu_dev_info *info;
> const int s_max = 3, ss_max = 3, eu_max = 8;
> int s, ss;
> - u32 fuse2, eu_disable[s_max], s_enable, ss_disable;
> + u32 fuse2, eu_disable[s_max], ss_disable;
> +
> + info = (struct sseu_dev_info *)&dev_priv->info.sseu;
>
> fuse2 = I915_READ(GEN8_FUSE2);
> - s_enable = (fuse2 & GEN8_F2_S_ENA_MASK) >> GEN8_F2_S_ENA_SHIFT;
> +
> + info->slice_mask = (fuse2 & GEN8_F2_S_ENA_MASK) >>
> + GEN8_F2_S_ENA_SHIFT;
> ss_disable = (fuse2 & GEN8_F2_SS_DIS_MASK) >> GEN8_F2_SS_DIS_SHIFT;
>
> eu_disable[0] = I915_READ(GEN8_EU_DISABLE0) & GEN8_EU_DIS0_S0_MASK;
> @@ -694,23 +697,20 @@ static void broadwell_sseu_info_init(struct drm_device *dev)
> (32 - GEN8_EU_DIS1_S2_SHIFT));
>
>
> - info = (struct sseu_dev_info *)&INTEL_INFO(dev_priv)->sseu;
> -
> - info->slice_total = hweight32(s_enable);
> -
> /*
> * The subslice disable field is global, i.e. it applies
> * to each of the enabled slices.
> */
> info->subslice_per_slice = ss_max - hweight32(ss_disable);
> - info->subslice_total = info->slice_total * info->subslice_per_slice;
> + info->subslice_total = hweight32(info->slice_mask) *
^ hweight8?
> + info->subslice_per_slice;
>
> /*
> * Iterate through enabled slices and subslices to
> * count the total enabled EU.
> */
> for (s = 0; s < s_max; s++) {
> - if (!(s_enable & (0x1 << s)))
> + if (!(info->slice_mask & BIT(s)))

(same about for_each set_bit)

> /* skip disabled slice */
> continue;
>
> @@ -745,7 +745,7 @@ static void broadwell_sseu_info_init(struct drm_device *dev)
> * BDW supports slice power gating on devices with more than
> * one slice.
> */
> - info->has_slice_pg = (info->slice_total > 1);
> + info->has_slice_pg = hweight32(info->slice_mask) > 1;
^ hweight8?
> info->has_subslice_pg = 0;
> info->has_eu_pg = 0;
> }
> @@ -825,7 +825,8 @@ static void intel_device_info_runtime_init(struct drm_device *dev)
> else if (INTEL_INFO(dev)->gen >= 9)
> gen9_sseu_info_init(dev);
>
> - DRM_DEBUG_DRIVER("slice total: %u\n", info->sseu.slice_total);
> + DRM_DEBUG_DRIVER("slice total: %u\n",
> + hweight32(info->sseu.slice_mask));
^ hweight8?
> DRM_DEBUG_DRIVER("subslice total: %u\n", info->sseu.subslice_total);
> DRM_DEBUG_DRIVER("subslice per slice: %u\n",
> info->sseu.subslice_per_slice);
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index cb0427d..7cc9ec8 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -783,7 +783,7 @@ struct intel_csr {
> #define SEP_SEMICOLON ;
>
> struct sseu_dev_info {
> - u8 slice_total;
> + u8 slice_mask;
> u8 subslice_total;
> u8 subslice_per_slice;
> u8 eu_total;
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 8a55f8a..4130ff1 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -2202,7 +2202,7 @@ make_rpcs(struct drm_device *dev)
> */
> if (INTEL_INFO(dev)->sseu.has_slice_pg) {
> rpcs |= GEN8_RPCS_S_CNT_ENABLE;
> - rpcs |= INTEL_INFO(dev)->sseu.slice_total <<
> + rpcs |= hweight32(INTEL_INFO(dev)->sseu.slice_mask) <<
^ hweight8?

> GEN8_RPCS_S_CNT_SHIFT;
> rpcs |= GEN8_RPCS_ENABLE;
> }

I'm not positive if hweight32 is actually okay on an 8bit type. I remember Ville
correcting me once on this, but I can't remember it's correct. Assuming
hweight32 is fine to use, with or without my recommendations, this is:
Reviewed-by: Ben Widawsky <benjamin.widawsky@intel.com>

--
Ben Widawsky, Intel Open Source Technology Center