drm/i915/chv: Tune L3 SQC credits based on actual latencies
While browsing BSpec I bumped into a note saying we need to tune these
values based on actual measurements done after initial enabling. I've
checked that it indeed improves things on BXT. I haven't checked this on
CHV, but here it is if someone wants to give it a go.
v2:
- Add note about the discrepancy wrt. to the spec in the formula
calculating the credit encodings. (Mika, Ville)
- Move the WA comment to the new function. (Ville)
v3:
- Keep the comment about the SQC WA in the caller. (Ville)
CC: Ville Syrjälä <ville.syrjala@linux.intel.com>
CC: Mika Kuoppala <mika.kuoppala@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1462280061-1457-4-git-send-email-imre.deak@intel.com
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 6a48f40..017c431 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -6696,11 +6696,33 @@
}
}
+static void gen8_set_l3sqc_credits(struct drm_i915_private *dev_priv,
+ int general_prio_credits,
+ int high_prio_credits)
+{
+ u32 misccpctl;
+
+ /* WaTempDisableDOPClkGating:bdw */
+ misccpctl = I915_READ(GEN7_MISCCPCTL);
+ I915_WRITE(GEN7_MISCCPCTL, misccpctl & ~GEN7_DOP_CLOCK_GATE_ENABLE);
+
+ I915_WRITE(GEN8_L3SQCREG1,
+ L3_GENERAL_PRIO_CREDITS(general_prio_credits) |
+ L3_HIGH_PRIO_CREDITS(high_prio_credits));
+
+ /*
+ * Wait at least 100 clocks before re-enabling clock gating.
+ * See the definition of L3SQCREG1 in BSpec.
+ */
+ POSTING_READ(GEN8_L3SQCREG1);
+ udelay(1);
+ I915_WRITE(GEN7_MISCCPCTL, misccpctl);
+}
+
static void broadwell_init_clock_gating(struct drm_device *dev)
{
struct drm_i915_private *dev_priv = dev->dev_private;
enum pipe pipe;
- uint32_t misccpctl;
ilk_init_lp_watermarks(dev);
@@ -6731,21 +6753,8 @@
I915_WRITE(GEN8_UCGCTL6, I915_READ(GEN8_UCGCTL6) |
GEN8_SDEUNIT_CLOCK_GATE_DISABLE);
- /*
- * WaProgramL3SqcReg1Default:bdw
- * WaTempDisableDOPClkGating:bdw
- */
- misccpctl = I915_READ(GEN7_MISCCPCTL);
- I915_WRITE(GEN7_MISCCPCTL, misccpctl & ~GEN7_DOP_CLOCK_GATE_ENABLE);
- I915_WRITE(GEN8_L3SQCREG1, L3_GENERAL_PRIO_CREDITS(30) |
- L3_HIGH_PRIO_CREDITS(2));
- /*
- * Wait at least 100 clocks before re-enabling clock gating. See
- * the definition of L3SQCREG1 in BSpec.
- */
- POSTING_READ(GEN8_L3SQCREG1);
- udelay(1);
- I915_WRITE(GEN7_MISCCPCTL, misccpctl);
+ /* WaProgramL3SqcReg1Default:bdw */
+ gen8_set_l3sqc_credits(dev_priv, 30, 2);
/*
* WaGttCachingOffByDefault:bdw
@@ -7016,6 +7025,13 @@
GEN8_SDEUNIT_CLOCK_GATE_DISABLE);
/*
+ * WaProgramL3SqcReg1Default:chv
+ * See gfxspecs/Related Documents/Performance Guide/
+ * LSQC Setting Recommendations.
+ */
+ gen8_set_l3sqc_credits(dev_priv, 38, 2);
+
+ /*
* GTT cache may not work with big pages, so if those
* are ever enabled GTT cache may need to be disabled.
*/