On Thu, 12 Nov 2015 10:35:00 +0200 Imre Deak <imre.deak@xxxxxxxxx> wrote: > On Wed, 2015-11-11 at 13:36 -0800, Bob Paauwe wrote: > > On Tue, 10 Nov 2015 11:04:22 +0200 > > Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx> wrote: > > > > > Bob Paauwe <bob.j.paauwe@xxxxxxxxx> writes: > > > > > > > Signed-off-by: Bob Paauwe <bob.j.paauwe@xxxxxxxxx> > > > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92768 > > > > --- > > > > drivers/gpu/drm/i915/intel_pm.c | 4 ++-- > > > > 1 file changed, 2 insertions(+), 2 deletions(-) > > > > > > > > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c > > > > index 647c0ff..fc5097f 100644 > > > > --- a/drivers/gpu/drm/i915/intel_pm.c > > > > +++ b/drivers/gpu/drm/i915/intel_pm.c > > > > @@ -7138,7 +7138,7 @@ static int chv_freq_opcode(struct drm_i915_private *dev_priv, int val) > > > > > > > > int intel_gpu_freq(struct drm_i915_private *dev_priv, int val) > > > > { > > > > - if (IS_GEN9(dev_priv->dev)) > > > > + if (IS_GEN9(dev_priv->dev) && !IS_BROXTON(dev_priv->dev)) > > > > return (val * GT_FREQUENCY_MULTIPLIER) / > > > > GEN9_FREQ_SCALER; > > > > > > Documentation disagrees with this patch. The units are 16.67Mhz > > > thus we should use 50/3. > > > > > > -Mika > > > > I'm not sure I trust the documentation in this case. Elsewhere, in > > gen6_init_rps_frequencies() we use GEN9_FREQ_SCALER for SKL only, not for BXT. > > On SKL the frequency _capability_ register uses 50MHz units, but the > frequency _request_ register uses 16.67MHz units. We store the frequency > limits in 16.67MHz units in rps.rp*_freq, hence the use of > GEN9_FREQ_SCALER in gen6_init_rps_frequencies(). When requesting a > frequency we only use GEN9_FREQ_SCALER to get the 16.67MHz constant > value. > > On BXT both the capability and request registers use 16.67MHz units, so > we don't need to convert in gen6_init_rps_frequencies(), but we still > use GEN9_FREQ_SCALER when requesting the frequency to get the 16.67MHz > constant value. > > Confusing like hell, but it works. That makes it a bit less confusing, thanks! Is this all documented somewhere? I'd like to read up on it so if you have any pointers please send me an email. > > > I tried changing gen6_init_rps_frequencies() to use it for both SKL and > > BXT but that didn't resolve the problem when running the ps_rps igt > > test. So if we really should be using the 50/3 scale for BXT, there's > > another bug somewhere. > > The problem is that atm we can't set the min/max frequencies via sysfs > to the same value that we read out from these same files, due to the > rounding down we do in the driver. Using round-to-closest is one way to > fix it I posted a patch to do this to the bug report. I saw your patch there, I'll give that a try. > > > > > else if (IS_CHERRYVIEW(dev_priv->dev)) > > > > return chv_gpu_freq(dev_priv, val); > > > > @@ -7150,7 +7150,7 @@ int intel_gpu_freq(struct drm_i915_private *dev_priv, int val) > > > > > > > > int intel_freq_opcode(struct drm_i915_private *dev_priv, int val) > > > > { > > > > - if (IS_GEN9(dev_priv->dev)) > > > > + if (IS_GEN9(dev_priv->dev) && !IS_BROXTON(dev_priv->dev)) > > > > return (val * GEN9_FREQ_SCALER) / GT_FREQUENCY_MULTIPLIER; > > > > else if (IS_CHERRYVIEW(dev_priv->dev)) > > > > return chv_freq_opcode(dev_priv, val); > > > > -- > > > > 2.4.3 > > > > > > > > _______________________________________________ > > > > Intel-gfx mailing list > > > > Intel-gfx@xxxxxxxxxxxxxxxxxxxxx > > > > http://lists.freedesktop.org/mailman/listinfo/intel-gfx > > > > > > > > -- -- Bob Paauwe Bob.J.Paauwe@xxxxxxxxx IOTG / PED Software Organization Intel Corp. Folsom, CA (916) 356-6193 _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
