On Fri, 13 Nov 2015 19:29:41 +0200 Mika Kuoppala <mika.kuoppala@xxxxxxxxxxxxxxx> wrote: > When we set and later readback a frequency value through > sysfs interface, igt/pm_rpm assumes that we get same value back > if it matches hw granularity. > > On bxt we have found out that this is not always the case. > Currently frequency - hw ratio - frequency conversions round down, > with few exceptions on platforms that have more specific conversions. > On bxt the supported range can be for example from 100Mhz to 650Mhz. > Midpoint is then calculated by test to be 375 which pm_rps uses to find a > closest hw supported frequency. That is 366 (ratio 22), > which it then writes back. But as the rounding down kicks in, > driver actually sets 350 instead of 366, as 366 is 2/3 below 22 * 50/3. > > Fix this by rounding to closest instead of rounding down in > freq-ratio-freq conversions. > > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=92768 > Testcase: igt/pm_rps/basic-api > Tested-by: Bob Paauwe <bob.j.paauwe@xxxxxxxxx> > Cc: Bob Paauwe <bob.j.paauwe@xxxxxxxxx> > Signed-off-by: Imre Deak <imre.deak@xxxxxxxxx> > Signed-off-by: Mika Kuoppala <mika.kuoppala@xxxxxxxxx> > --- > drivers/gpu/drm/i915/intel_pm.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c > index 647c0ff..740623f 100644 > --- a/drivers/gpu/drm/i915/intel_pm.c > +++ b/drivers/gpu/drm/i915/intel_pm.c > @@ -7139,7 +7139,8 @@ 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)) > - return (val * GT_FREQUENCY_MULTIPLIER) / GEN9_FREQ_SCALER; > + return DIV_ROUND_CLOSEST(val * GT_FREQUENCY_MULTIPLIER, > + GEN9_FREQ_SCALER); > else if (IS_CHERRYVIEW(dev_priv->dev)) > return chv_gpu_freq(dev_priv, val); > else if (IS_VALLEYVIEW(dev_priv->dev)) > @@ -7151,13 +7152,14 @@ 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)) > - return (val * GEN9_FREQ_SCALER) / GT_FREQUENCY_MULTIPLIER; > + return DIV_ROUND_CLOSEST(val * GEN9_FREQ_SCALER, > + GT_FREQUENCY_MULTIPLIER); > else if (IS_CHERRYVIEW(dev_priv->dev)) > return chv_freq_opcode(dev_priv, val); > else if (IS_VALLEYVIEW(dev_priv->dev)) > return byt_freq_opcode(dev_priv, val); > else > - return val / GT_FREQUENCY_MULTIPLIER; > + return DIV_ROUND_CLOSEST(val, GT_FREQUENCY_MULTIPLIER); > } > > struct request_boost { Reviewed-by: Bob Paauwe <bob.j.paauwe@xxxxxxxxx> -- -- 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
