WaProgramMgsrForCorrectSliceSpecificMmioReads dictate 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. Otherwise, incorrect value will be returned.
However, that means each subsequent MMIO read will be forwarded to a
specific slice/subslice combination as read is unicast. This is OK since
slice/subslice specific register values are consistent in almost all cases
across slice/subslice. There are rare occasions such as INSTDONE that this
value will be dependent on slice/subslice combo, in such cases, we need to
program 0xFDC and recover this after. This is already covered by
read_subslice_reg for INSTDONE.
Also, 0xFDC will lose its information after TDR/engine reset/power state
change.
Signed-off-by: Yunwei Zhang <yunwei.zhang@xxxxxxxxx>
Cc: Oscar Mateo <oscar.mateo@xxxxxxxxx>
Cc: Michel Thierry <michel.thierry@xxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_engine_cs.c | 43 ++++++++++++++++++++++++++++++++--
1 file changed, 41 insertions(+), 2 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index a2b1e9e..bc8fed7 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -781,6 +781,29 @@ const char *i915_cache_level_str(struct drm_i915_private *i915, int type)
}
}
+static u32 calculate_mcr(u32 mcr, struct drm_i915_private *dev_priv)
+{
+ const struct sseu_dev_info *sseu = &(INTEL_INFO(dev_priv)->sseu);
+ u32 slice = find_last_bit((unsigned long *)&(sseu->slice_mask),
+ sizeof(sseu->slice_mask));
+ u32 subslice = find_last_bit((unsigned long *)&(sseu->subslice_mask[slice]),
+ sizeof(sseu->subslice_mask[0]));
+
+ mcr &= ~(GEN8_MCR_SLICE_MASK | GEN8_MCR_SUBSLICE_MASK);
+ mcr |= GEN8_MCR_SLICE(slice) | GEN8_MCR_SUBSLICE(subslice);
+
+ return mcr;
+}
+
+static void wa_init_mcr(struct drm_i915_private *dev_priv)
+{
+ u32 mcr;
+
+ mcr = I915_READ(GEN8_MCR_SELECTOR);
+ mcr = calculate_mcr(mcr, dev_priv);
+ I915_WRITE(GEN8_MCR_SELECTOR, mcr);
+}
+
static inline uint32_t
read_subslice_reg(struct drm_i915_private *dev_priv, int slice,
int subslice, i915_reg_t reg)
@@ -799,18 +822,31 @@ read_subslice_reg(struct drm_i915_private *dev_priv, int slice,
intel_uncore_forcewake_get__locked(dev_priv, fw_domains);
mcr = I915_READ_FW(GEN8_MCR_SELECTOR);
+
/*
* The HW expects the slice and sublice selectors to be reset to 0
* after reading out the registers.
*/
- WARN_ON_ONCE(mcr & (GEN8_MCR_SLICE_MASK | GEN8_MCR_SUBSLICE_MASK));
+ if (INTEL_GEN(dev_priv) < 10)
+ WARN_ON_ONCE(mcr & (GEN8_MCR_SLICE_MASK |
+ GEN8_MCR_SUBSLICE_MASK));
+
mcr &= ~(GEN8_MCR_SLICE_MASK | GEN8_MCR_SUBSLICE_MASK);
mcr |= GEN8_MCR_SLICE(slice) | GEN8_MCR_SUBSLICE(subslice);
I915_WRITE_FW(GEN8_MCR_SELECTOR, mcr);
ret = I915_READ_FW(reg);
- mcr &= ~(GEN8_MCR_SLICE_MASK | GEN8_MCR_SUBSLICE_MASK);
+ /*
+ * WaProgramMgsrForCorrectSliceSpecificMmioReads:cnl
+ * expects mcr to be programed to a enabled slice/subslice pair
+ * before any MMIO read into slice/subslice register
+ */
+ if (INTEL_GEN(dev_priv) < 10)
+ mcr &= ~(GEN8_MCR_SLICE_MASK | GEN8_MCR_SUBSLICE_MASK);
+ else
+ mcr = calculate_mcr(mcr, dev_priv);
+
I915_WRITE_FW(GEN8_MCR_SELECTOR, mcr);
intel_uncore_forcewake_put__locked(dev_priv, fw_domains);
@@ -1278,6 +1314,9 @@ static int cnl_init_workarounds(struct intel_engine_cs *engine)
struct drm_i915_private *dev_priv = engine->i915;
int ret;
+ /* WaProgramMgsrForCorrectSliceSpecificMmioReads: cnl */
+ wa_init_mcr(dev_priv);
+
/* WaDisableI2mCycleOnWRPort:cnl (pre-prod) */
if (IS_CNL_REVID(dev_priv, CNL_REVID_B0, CNL_REVID_B0))
I915_WRITE(GAMT_CHKN_BIT_REG,
--
2.7.4
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