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.
Also, 0xFDC will lose its information after TDR/engine reset/power state
change.
References: HSD#1405586840, BSID#0575
v2:
- use fls() instead of find_last_bit() (Chris)
- added INTEL_SSEU to extract sseu from device info. (Chris)
v3:
- rebase on latest tip
v5:
- Added references (Mika)
- Change the ordered of passing arguments and etc. (Ursulin)
v6:
- Updated the comment that conflict with the patch. (Chris)
Cc: Oscar Mateo <oscar.ma...@intel.com>
Cc: Michel Thierry <michel.thie...@intel.com>
Cc: Joonas Lahtinen <joonas.lahti...@linux.intel.com>
Cc: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuopp...@linux.intel.com>
Cc: Tvrtko Ursulin <tvrtko.ursu...@linux.intel.com>
Signed-off-by: Yunwei Zhang <yunwei.zh...@intel.com>
---
drivers/gpu/drm/i915/intel_engine_cs.c | 42 +++++++++++++++++++++++++++++++---
1 file changed, 39 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c
b/drivers/gpu/drm/i915/intel_engine_cs.c
index 12486d8..4c50bee 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -796,6 +796,27 @@ const char *i915_cache_level_str(struct drm_i915_private
*i915, int type)
}
}
+static u32 calculate_mcr(struct drm_i915_private *dev_priv, u32 mcr)
+{
+ const struct sseu_dev_info *sseu = &(INTEL_INFO(dev_priv)->sseu);
+ u32 slice = fls(sseu->slice_mask);
+ u32 subslice = fls(sseu->subslice_mask[slice]);
+
+ 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(dev_priv, mcr);
+ 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)
@@ -828,18 +849,30 @@ 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.
+ * before GEN10 or to a enabled s/ss post GEN10 after reading out the
+ * registers.
*/
- WARN_ON_ONCE(mcr & mcr_slice_subslice_mask);
+ WARN_ON_ONCE(INTEL_GEN(dev_priv) < 10 &&
+ (mcr & mcr_slice_subslice_mask));
mcr &= ~mcr_slice_subslice_mask;
mcr |= mcr_slice_subslice_select;
I915_WRITE_FW(GEN8_MCR_SELECTOR, mcr);
ret = I915_READ_FW(reg);
- mcr &= ~mcr_slice_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 &= ~mcr_slice_subslice_mask;
+ else
+ mcr = calculate_mcr(dev_priv, mcr);
+
I915_WRITE_FW(GEN8_MCR_SELECTOR, mcr);
intel_uncore_forcewake_put__locked(dev_priv, fw_domains);
@@ -1307,6 +1340,9 @@ 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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