[Intel-gfx] [PATCH] drm/i915: Extend residency counter ranges on chv and byt

[Mika Kuoppala]

We were passively acting on the high counter value bit
and as it was never set, we were only utilizing the
the 32bits of resolution. As the divisor with these platforms
is quite high, the wrap around happened in the less than 13 seconds.

If we toggle the resolution bit in the control register and
read twice we can get 8 bits more, bringing the wrap in
54 minute range.

Reported-by: Len Brown <len.brown at intel.com>
Cc: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
Cc: Len Brown <len.brown at intel.com>
Signed-off-by: Mika Kuoppala <mika.kuoppala at intel.com>
---
 drivers/gpu/drm/i915/i915_sysfs.c | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
index af0ac9f..807d7be 100644
--- a/drivers/gpu/drm/i915/i915_sysfs.c
+++ b/drivers/gpu/drm/i915/i915_sysfs.c
@@ -53,17 +53,26 @@ static u32 calc_residency(struct drm_i915_private *dev_priv,
 
 	/* On VLV and CHV, residency time is in CZ units rather than 1.28us */
 	if (IS_VALLEYVIEW(dev_priv) || IS_CHERRYVIEW(dev_priv)) {
-		units = 1;
+		u32 lower, upper;
 		div = dev_priv->czclk_freq;
 
-		if (I915_READ(VLV_COUNTER_CONTROL) & VLV_COUNT_RANGE_HIGH)
-			units <<= 8;
+		I915_WRITE(VLV_COUNTER_CONTROL,
+			   _MASKED_BIT_ENABLE(VLV_COUNT_RANGE_HIGH));
+		upper = I915_READ(reg);
+
+		I915_WRITE(VLV_COUNTER_CONTROL,
+			   _MASKED_BIT_DISABLE(VLV_COUNT_RANGE_HIGH));
+		lower = I915_READ(reg);
+
+		raw_time = lower | (u64)upper << 8;
+		goto out;
 	} else if (IS_GEN9_LP(dev_priv)) {
 		units = 1;
 		div = 1200;		/* 833.33ns */
 	}
 
 	raw_time = I915_READ(reg) * units;
+ out:
 	ret = DIV_ROUND_UP_ULL(raw_time, div);
 
 	intel_runtime_pm_put(dev_priv);
-- 
2.7.4