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)
v7:
- Moved WA explanation Comments(Oscar)
- Rebased.
Cc: Oscar Mateo <oscar.mateo@xxxxxxxxx>
Cc: Michel Thierry <michel.thierry@xxxxxxxxx>
Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx>
Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxxxxxxx>
Signed-off-by: Yunwei Zhang <yunwei.zhang@xxxxxxxxx>
---
drivers/gpu/drm/i915/i915_drv.h | 2 ++
drivers/gpu/drm/i915/intel_engine_cs.c | 36 +++++++++++++++++++++++++++++---
drivers/gpu/drm/i915/intel_workarounds.c | 12 +++++++++++
3 files changed, 47 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 34c125e..f1ec334 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2743,6 +2743,8 @@ int vlv_force_gfx_clock(struct drm_i915_private *dev_priv, bool on);
int intel_engines_init_mmio(struct drm_i915_private *dev_priv);
int intel_engines_init(struct drm_i915_private *dev_priv);
+u32 intel_sanitize_mcr(struct drm_i915_private *dev_priv, u32 mcr);
+
/* intel_hotplug.c */
void intel_hpd_irq_handler(struct drm_i915_private *dev_priv,
u32 pin_mask, u32 long_mask);
diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c
index 6bfd7e3..af58cd4 100644
--- a/drivers/gpu/drm/i915/intel_engine_cs.c
+++ b/drivers/gpu/drm/i915/intel_engine_cs.c
@@ -780,6 +780,29 @@ const char *i915_cache_level_str(struct drm_i915_private *i915, int type)
}
}
+u32 intel_sanitize_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]);
+
+ /*
+ * WaProgramMgsrForCorrectSliceSpecificMmioReads:cnl
+ * 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.
+ */
+ mcr &= ~(GEN8_MCR_SLICE_MASK | GEN8_MCR_SUBSLICE_MASK);
+ mcr |= GEN8_MCR_SLICE(slice) | GEN8_MCR_SUBSLICE(subslice);
+
+ return mcr;
+}
+
static inline uint32_t
read_subslice_reg(struct drm_i915_private *dev_priv, int slice,
int subslice, i915_reg_t reg)
@@ -812,18 +835,25 @@ 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;
+ if (INTEL_GEN(dev_priv) < 10)
+ mcr &= ~mcr_slice_subslice_mask;
+ else
+ mcr = intel_sanitize_mcr(dev_priv, mcr);
+
I915_WRITE_FW(GEN8_MCR_SELECTOR, mcr);
intel_uncore_forcewake_put__locked(dev_priv, fw_domains);
diff --git a/drivers/gpu/drm/i915/intel_workarounds.c b/drivers/gpu/drm/i915/intel_workarounds.c
index 2df3538..9bdac97 100644
--- a/drivers/gpu/drm/i915/intel_workarounds.c
+++ b/drivers/gpu/drm/i915/intel_workarounds.c
@@ -672,8 +672,20 @@ static void cfl_gt_workarounds_apply(struct drm_i915_private *dev_priv)
GAMT_ECO_ENABLE_IN_PLACE_DECOMPRESS);
}
+static void wa_init_mcr(struct drm_i915_private *dev_priv)
+{
+ u32 mcr;
+
+ mcr = I915_READ(GEN8_MCR_SELECTOR);
+ mcr = intel_sanitize_mcr(dev_priv, mcr);
+ I915_WRITE(GEN8_MCR_SELECTOR, mcr);
+}
+
static void cnl_gt_workarounds_apply(struct drm_i915_private *dev_priv)
{
+ /* 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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