Re: [CI,5/5] drm/i915: Expand subslice mask

Jani Nikula
2019-05-29T14:30:36Z

On Wed, 29 May 2019, Nathan Chancellor <natechancellor@gmail.com> wrote:
> Hi Stuart,
>
> On Fri, May 24, 2019 at 08:40:22AM -0700, Stuart Summers wrote:
>> Currently, the subslice_mask runtime parameter is stored as an
>> array of subslices per slice. Expand the subslice mask array to
>> better match what is presented to userspace through the
>> I915_QUERY_TOPOLOGY_INFO ioctl. The index into this array is
>> then calculated:
>> slice * subslice stride + subslice index / 8
>>
>> v2: fix spacing in set_sseu_info args
>> use set_sseu_info to initialize sseu data when building
>> device status in debugfs
>> rename variables in intel_engine_types.h to avoid checkpatch
>> warnings
>> v3: update headers in intel_sseu.h
>> v4: add const to some sseu_dev_info variables
>> use sseu->eu_stride for EU stride calculations
>> v5: address review comments from Tvrtko and Daniele
>> v6: remove extra space in intel_sseu_get_subslices
>> return the correct subslice enable in for_each_instdone
>> add GEM_BUG_ON to ensure user doesn't pass invalid ss_mask size
>> use printk formatted string for subslice mask
>> v7: remove string.h header and rebase
>>
>> Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>> Cc: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
>> Acked-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>
>> Reviewed-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
>> Signed-off-by: Stuart Summers <stuart.summers@intel.com>
>> ---
>
> <snip>
>
>> diff --git a/drivers/gpu/drm/i915/intel_device_info.c b/drivers/gpu/drm/i915/intel_device_info.c
>> index 97f742530fa1..3625f777f3a3 100644
>> --- a/drivers/gpu/drm/i915/intel_device_info.c
>> +++ b/drivers/gpu/drm/i915/intel_device_info.c
>> @@ -92,9 +92,9 @@ static void sseu_dump(const struct sseu_dev_info *sseu, struct drm_printer *p)
>> hweight8(sseu->slice_mask), sseu->slice_mask);
>> drm_printf(p, "subslice total: %u\n", intel_sseu_subslice_total(sseu));
>> for (s = 0; s < sseu->max_slices; s++) {
>> - drm_printf(p, "slice%d: %u subslices, mask=%04x\n",
>> + drm_printf(p, "slice%d: %u subslices, mask=%08x\n",
>> s, intel_sseu_subslices_per_slice(sseu, s),
>> - sseu->subslice_mask[s]);
>> + intel_sseu_get_subslices(sseu, s));
>> }
>> drm_printf(p, "EU total: %u\n", sseu->eu_total);
>> drm_printf(p, "EU per subslice: %u\n", sseu->eu_per_subslice);
>> @@ -117,10 +117,9 @@ void intel_device_info_dump_runtime(const struct intel_runtime_info *info,
>> static int sseu_eu_idx(const struct sseu_dev_info *sseu, int slice,
>> int subslice)
>> {
>> - int subslice_stride = GEN_SSEU_STRIDE(sseu->max_eus_per_subslice);
>> - int slice_stride = sseu->max_subslices * subslice_stride;
>> + int slice_stride = sseu->max_subslices * sseu->eu_stride;
>>
>> - return slice * slice_stride + subslice * subslice_stride;
>> + return slice * slice_stride + subslice * sseu->eu_stride;
>> }
>>
>> static u16 sseu_get_eus(const struct sseu_dev_info *sseu, int slice,
>> @@ -129,7 +128,7 @@ static u16 sseu_get_eus(const struct sseu_dev_info *sseu, int slice,
>> int i, offset = sseu_eu_idx(sseu, slice, subslice);
>> u16 eu_mask = 0;
>>
>> - for (i = 0; i < GEN_SSEU_STRIDE(sseu->max_eus_per_subslice); i++) {
>> + for (i = 0; i < sseu->eu_stride; i++) {
>> eu_mask |= ((u16)sseu->eu_mask[offset + i]) <<
>> (i * BITS_PER_BYTE);
>> }
>> @@ -142,7 +141,7 @@ static void sseu_set_eus(struct sseu_dev_info *sseu, int slice, int subslice,
>> {
>> int i, offset = sseu_eu_idx(sseu, slice, subslice);
>>
>> - for (i = 0; i < GEN_SSEU_STRIDE(sseu->max_eus_per_subslice); i++) {
>> + for (i = 0; i < sseu->eu_stride; i++) {
>> sseu->eu_mask[offset + i] =
>> (eu_mask >> (BITS_PER_BYTE * i)) & 0xff;
>> }
>> @@ -159,9 +158,9 @@ void intel_device_info_dump_topology(const struct sseu_dev_info *sseu,
>> }
>>
>> for (s = 0; s < sseu->max_slices; s++) {
>> - drm_printf(p, "slice%d: %u subslice(s) (0x%hhx):\n",
>> + drm_printf(p, "slice%d: %u subslice(s) (0x%08x):\n",
>> s, intel_sseu_subslices_per_slice(sseu, s),
>> - sseu->subslice_mask[s]);
>> + intel_sseu_get_subslices(sseu, s));
>>
>> for (ss = 0; ss < sseu->max_subslices; ss++) {
>> u16 enabled_eus = sseu_get_eus(sseu, s, ss);
>> @@ -190,15 +189,10 @@ static void gen11_sseu_info_init(struct drm_i915_private *dev_priv)
>> u8 eu_en;
>> int s;
>>
>> - if (IS_ELKHARTLAKE(dev_priv)) {
>> - sseu->max_slices = 1;
>> - sseu->max_subslices = 4;
>> - sseu->max_eus_per_subslice = 8;
>> - } else {
>> - sseu->max_slices = 1;
>> - sseu->max_subslices = 8;
>> - sseu->max_eus_per_subslice = 8;
>> - }
>> + if (IS_ELKHARTLAKE(dev_priv))
>> + intel_sseu_set_info(sseu, 1, 4, 8);
>> + else
>> + intel_sseu_set_info(sseu, 1, 8, 8);
>>
>> s_en = I915_READ(GEN11_GT_SLICE_ENABLE) & GEN11_GT_S_ENA_MASK;
>> ss_en = ~I915_READ(GEN11_GT_SUBSLICE_DISABLE);
>> @@ -207,15 +201,15 @@ static void gen11_sseu_info_init(struct drm_i915_private *dev_priv)
>>
>> for (s = 0; s < sseu->max_slices; s++) {
>> if (s_en & BIT(s)) {
>> - int ss_idx = sseu->max_subslices * s;
>> int ss;
>>
>> sseu->slice_mask |= BIT(s);
>> - sseu->subslice_mask[s] = (ss_en >> ss_idx) & ss_en_mask;
>> - for (ss = 0; ss < sseu->max_subslices; ss++) {
>> - if (sseu->subslice_mask[s] & BIT(ss))
>> +
>> + intel_sseu_set_subslices(sseu, s, ss_en_mask);
>> +
>> + for (ss = 0; ss < sseu->max_subslices; ss++)
>> + if (intel_sseu_has_subslice(sseu, s, ss))
>> sseu_set_eus(sseu, s, ss, eu_en);
>> - }
>> }
>> }
>> sseu->eu_per_subslice = hweight8(eu_en);
>> @@ -235,23 +229,10 @@ static void gen10_sseu_info_init(struct drm_i915_private *dev_priv)
>> const int eu_mask = 0xff;
>> u32 subslice_mask, eu_en;
>>
>> + intel_sseu_set_info(sseu, 6, 4, 8);
>> +
>> sseu->slice_mask = (fuse2 & GEN10_F2_S_ENA_MASK) >>
>> GEN10_F2_S_ENA_SHIFT;
>> - sseu->max_slices = 6;
>> - sseu->max_subslices = 4;
>> - sseu->max_eus_per_subslice = 8;
>> -
>> - subslice_mask = (1 << 4) - 1;
>> - subslice_mask &= ~((fuse2 & GEN10_F2_SS_DIS_MASK) >>
>> - GEN10_F2_SS_DIS_SHIFT);
>> -
>> - /*
>> - * Slice0 can have up to 3 subslices, but there are only 2 in
>> - * slice1/2.
>> - */
>> - sseu->subslice_mask[0] = subslice_mask;
>> - for (s = 1; s < sseu->max_slices; s++)
>> - sseu->subslice_mask[s] = subslice_mask & 0x3;
>>
>> /* Slice0 */
>> eu_en = ~I915_READ(GEN8_EU_DISABLE0);
>> @@ -276,14 +257,22 @@ static void gen10_sseu_info_init(struct drm_i915_private *dev_priv)
>> eu_en = ~I915_READ(GEN10_EU_DISABLE3);
>> sseu_set_eus(sseu, 5, 1, eu_en & eu_mask);
>>
>> - /* Do a second pass where we mark the subslices disabled if all their
>> - * eus are off.
>> - */
>> + subslice_mask = (1 << 4) - 1;
>> + subslice_mask &= ~((fuse2 & GEN10_F2_SS_DIS_MASK) >>
>> + GEN10_F2_SS_DIS_SHIFT);
>> +
>> for (s = 0; s < sseu->max_slices; s++) {
>> for (ss = 0; ss < sseu->max_subslices; ss++) {
>> if (sseu_get_eus(sseu, s, ss) == 0)
>> - sseu->subslice_mask[s] &= ~BIT(ss);
>> + subslice_mask &= ~BIT(ss);
>> }
>> +
>> + /*
>> + * Slice0 can have up to 3 subslices, but there are only 2 in
>> + * slice1/2.
>> + */
>> + intel_sseu_set_subslices(sseu, s, s == 0 ? subslice_mask :
>> + subslice_mask & 0x3);
>> }
>>
>> sseu->eu_total = compute_eu_total(sseu);
>> @@ -309,13 +298,12 @@ static void cherryview_sseu_info_init(struct drm_i915_private *dev_priv)
>> {
>> struct sseu_dev_info *sseu = &RUNTIME_INFO(dev_priv)->sseu;
>> u32 fuse;
>> + u8 subslice_mask;
>>
>> fuse = I915_READ(CHV_FUSE_GT);
>>
>> sseu->slice_mask = BIT(0);
>> - sseu->max_slices = 1;
>> - sseu->max_subslices = 2;
>> - sseu->max_eus_per_subslice = 8;
>> + intel_sseu_set_info(sseu, 1, 2, 8);
>>
>> if (!(fuse & CHV_FGT_DISABLE_SS0)) {
>> u8 disabled_mask =
>> @@ -324,7 +312,7 @@ static void cherryview_sseu_info_init(struct drm_i915_private *dev_priv)
>> (((fuse & CHV_FGT_EU_DIS_SS0_R1_MASK) >>
>> CHV_FGT_EU_DIS_SS0_R1_SHIFT) << 4);
>>
>> - sseu->subslice_mask[0] |= BIT(0);
>> + subslice_mask |= BIT(0);
>
> When building with -Wuninitialized, clang warns:
>
> drivers/gpu/drm/i915/intel_device_info.c:315:3: warning: variable 'subslice_mask' is uninitialized when used here [-Wuninitialized]
> subslice_mask |= BIT(0);
> ^~~~~~~~~~~~~
> drivers/gpu/drm/i915/intel_device_info.c:301:18: note: initialize the variable 'subslice_mask' to silence this warning
> u8 subslice_mask;
> ^
> = '\0'
>
> I assume that it should be initialized to zero but maybe you intended
> something different?

As it happens, the commit has been reverted for other reasons, and we
(the royal we, I really mean Stuart) can fix this while at it. ;)

BR,
Jani.

--
Jani Nikula, Intel Open Source Graphics Center