Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes: > On Thu, Mar 02, 2017 at 08:01:40PM +0200, Mika Kuoppala wrote: >> 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@xxxxxxxxx> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=94852 >> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> >> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> >> Cc: Len Brown <len.brown@xxxxxxxxx> >> Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> >> --- >> 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); > > Is this true??? There is an internal 40bit counter to which we have a > 32bit window (i.e. changing the counter control doesn't reset the > count). Yes, evidence suggests so with prod byt. But I am not sure if same holds true with chv. > > Note that you should recheck the high range afterwards to guard against > constructing an erroneous value across wraparound. And this should also > leave it set to high for other users on vlv. Other user being debugs? Perhaps u64 utility function to read it from both places then. -Mika > -Chris > > -- > Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
