The high counter value bit can be used to get 8 bits more
of range out of the same residency counter registers.
Lets toggle this bit on and off on vlv/chv while reading the
counters to push the wrap from 13 seconds to 54 minutes.
Reported-by: Len Brown <len.br...@intel.com>
Cc: Chris Wilson <ch...@chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrj...@linux.intel.com>
Signed-off-by: Mika Kuoppala <mika.kuopp...@intel.com>
---
drivers/gpu/drm/i915/intel_pm.c | 47 +++++++++++++++++++++++++++++++++++++----
1 file changed, 43 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index da742a9..7e7a8d9 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -8350,6 +8350,44 @@ void intel_pm_setup(struct drm_i915_private *dev_priv)
atomic_set(&dev_priv->pm.wakeref_count, 0);
}
+static u64 vlv_residency_raw(struct drm_i915_private *dev_priv,
+ const i915_reg_t reg)
+{
+ u32 lower, upper, tmp, saved_ctl;
+
+ /* The register accessed do not need forcewake. We borrow
+ * uncore lock to prevent concurrent access to range reg.
+ */
+ spin_lock_irq(&dev_priv->uncore.lock);
+ saved_ctl = I915_READ_FW(VLV_COUNTER_CONTROL);
+
+ if (!(saved_ctl & VLV_COUNT_RANGE_HIGH))
+ I915_WRITE_FW(VLV_COUNTER_CONTROL,
+ _MASKED_BIT_ENABLE(VLV_COUNT_RANGE_HIGH));
+
+ tmp = I915_READ_FW(reg);
+ do {
+ upper = tmp;
+
+ I915_WRITE_FW(VLV_COUNTER_CONTROL,
+ _MASKED_BIT_DISABLE(VLV_COUNT_RANGE_HIGH));
+ lower = I915_READ_FW(reg);
+
+ I915_WRITE_FW(VLV_COUNTER_CONTROL,
+ _MASKED_BIT_ENABLE(VLV_COUNT_RANGE_HIGH));
+
+ tmp = I915_READ_FW(reg);
+ } while (upper != tmp);
+
+ if (!(saved_ctl & VLV_COUNT_RANGE_HIGH))
+ I915_WRITE_FW(VLV_COUNTER_CONTROL,
+ _MASKED_BIT_DISABLE(VLV_COUNT_RANGE_HIGH));
+
+ spin_unlock_irq(&dev_priv->uncore.lock);
+
+ return lower | (u64)upper << 8;
+}
+
u64 intel_rc6_residency_us(struct drm_i915_private *dev_priv,
const i915_reg_t reg)
{
@@ -8367,15 +8405,16 @@ u64 intel_rc6_residency_us(struct drm_i915_private
*dev_priv,
units = 1000;
div = dev_priv->czclk_freq;
- if (I915_READ(VLV_COUNTER_CONTROL) & VLV_COUNT_RANGE_HIGH)
- units <<= 8;
+ raw_time = vlv_residency_raw(dev_priv, reg);
+ goto out;
} else if (IS_GEN9_LP(dev_priv)) {
units = 1000;
div = 1200; /* 833.33ns */
}
- raw_time = I915_READ(reg) * units;
- ret = DIV_ROUND_UP_ULL(raw_time, div);
+ raw_time = I915_READ(reg);
+out:
+ ret = DIV_ROUND_UP_ULL(raw_time * units, div);
intel_runtime_pm_put(dev_priv);
return ret;
--
2.7.4
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