[Intel-gfx] [PATCH v4] drm/i915: Enable WaProgramMgsrForCorrectSliceSpecificMmioReads for Gen9

Cooper Chiou
2021-03-03T18:25:45Z

WaProgramMgsrForCorrectSliceSpecificMmioReads applies for Gen9 to
resolve VP8 hardware encoding system hang up on GT1 sku for
ChromiumOS projects

Slice specific MMIO read inaccurate so MGSR needs to be programmed
appropriately to get correct reads from these slicet-related MMIOs.

It dictates that before any MMIO read into Slice/Subslice specific
registers, MCR packet control register(0xFDC) needs to be programmed
to point to any enabled slice/subslice pair, especially GT1 fused sku
since this issue can be reproduced on VP8 hardware encoding via ffmpeg
on ChromiumOS devices.
When exit PC7, MGSR will reset so that we have to skip fused subslice ID.

Reference: HSD#1508045018,1405586840, BSID#0575

Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Jani Nikula <jani.nikula@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: William Tseng <william.tseng@intel.com>
Cc: Lee Shawn C <shawn.c.lee@intel.com>

Signed-off-by: Cooper Chiou <cooper.chiou@intel.com>
---
drivers/gpu/drm/i915/gt/intel_workarounds.c | 37 +++++++++++++++++++++
1 file changed, 37 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/intel_workarounds.c b/drivers/gpu/drm/i915/gt/intel_workarounds.c
index 3b4a7da60f0b..59d1d12c959b 100644
--- a/drivers/gpu/drm/i915/gt/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/gt/intel_workarounds.c
@@ -878,9 +878,46 @@ hsw_gt_workarounds_init(struct drm_i915_private *i915, struct i915_wa_list *wal)
wa_write_clr(wal, GEN7_FF_THREAD_MODE, GEN7_FF_VS_REF_CNT_FFME);
}

+static void
+gen9_wa_init_mcr(struct drm_i915_private *i915, struct i915_wa_list *wal)
+{
+ const struct sseu_dev_info *sseu = &i915->gt.info.sseu;
+ unsigned int slice, subslice;
+ u32 mcr, mcr_mask;
+
+ GEM_BUG_ON(INTEL_GEN(i915) < 9);
+
+ /*
+ * WaProgramMgsrForCorrectSliceSpecificMmioReads:glk,kbl,cml
+ * Before any MMIO read into slice/subslice specific registers, MCR
+ * packet control register needs to be programmed to point to any
+ * enabled s/ss pair. Otherwise, incorrect values will be returned.
+ * This means each subsequent MMIO read will be forwarded to an
+ * specific s/ss combination, but this is OK since these registers
+ * are consistent across s/ss in almost all cases. In the rare
+ * occasions, such as INSTDONE, where this value is dependent
+ * on s/ss combo, the read should be done with read_subslice_reg.
+ */
+ slice = fls(sseu->slice_mask) - 1;
+ GEM_BUG_ON(slice >= ARRAY_SIZE(sseu->subslice_mask));
+ subslice = fls(intel_sseu_get_subslices(sseu, slice));
+ GEM_BUG_ON(!subslice);
+ subslice--;
+
+ mcr = GEN8_MCR_SLICE(slice) | GEN8_MCR_SUBSLICE(subslice);
+ mcr_mask = GEN8_MCR_SLICE_MASK | GEN8_MCR_SUBSLICE_MASK;
+
+ drm_dbg(&i915->drm, "MCR slice:%d/subslice:%d = %x\n", slice, subslice, mcr);
+
+ wa_write_clr_set(wal, GEN8_MCR_SELECTOR, mcr_mask, mcr);
+}
+
static void
gen9_gt_workarounds_init(struct drm_i915_private *i915, struct i915_wa_list *wal)
{
+ /* WaProgramMgsrForCorrectSliceSpecificMmioReads:glk,kbl,cml,gen9 */
+ gen9_wa_init_mcr(i915, wal);
+
/* WaDisableKillLogic:bxt,skl,kbl */
if (!IS_COFFEELAKE(i915) && !IS_COMETLAKE(i915))
wa_write_or(wal,
--
2.17.1