<div dir="ltr"> <div class="gmail_extra"> <div class="gmail_quote">On Wed, Apr 12, 2017 at 1:34 PM, Matthew Auld <<a href="mailto:matthew.william.auld@gmail.com" target="_blank">matthew.william.auld@gmail.com</a>> wrote: <blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">On 5 April 2017 at 20:05, Robert Bragg <<a href="mailto:robert@sixbynine.org">robert@sixbynine.org</a>> wrote: > An oa_exponent_to_ns() utility and per-gen timebase constants where were <div><div class="h5"> > recently removed when updating the tail pointer race condition WA, and > this restores those so we can update the _PROP_OA_EXPONENT validation > done in read_properties_unlocked() to not assume we have a 12.5MHz > timebase as we did for Haswell. > > Accordingly the oa_sample_rate_hard_limit value that's referenced by > proc_dointvec_minmax defining the absolute limit for the OA sampling > frequency is now initialized to (timestamp_frequency / 2) instead of the > 6.25MHz constant for Haswell. > > v2: > Specify frequency of 19.2MHz for BXT (Ville) > Initialize oa_sample_rate_hard_limit per-gen too (Lionel) > > Signed-off-by: Robert Bragg <<a href="mailto:robert@sixbynine.org">robert@sixbynine.org</a>> > Cc: Lionel Landwerlin <<a href="mailto:lionel.g.landwerlin@linux.intel.com">lionel.g.landwerlin@linux.intel.com</a>> > Cc: Ville Syrjälä <<a href="mailto:ville.syrjala@linux.intel.com">ville.syrjala@linux.intel.com</a>> > --- > drivers/gpu/drm/i915/i915_drv.h | 1 + > drivers/gpu/drm/i915/i915_perf.c | 31 ++++++++++++++++++++++--------- > 2 files changed, 23 insertions(+), 9 deletions(-) > > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h > index 3a22b6fd0ee6..48b07d706f06 100644 > --- a/drivers/gpu/drm/i915/i915_drv.h > +++ b/drivers/gpu/drm/i915/i915_drv.h > @@ -2463,6 +2463,7 @@ struct drm_i915_private { > > bool periodic; > int period_exponent; > + int timestamp_frequency; > > int metrics_set; > > diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c > index 98eb6415b63a..980b4a1fd7cc 100644 > --- a/drivers/gpu/drm/i915/i915_perf.c > +++ b/drivers/gpu/drm/i915/i915_perf.c > @@ -288,10 +288,12 @@ static u32 i915_perf_stream_paranoid = true; > > /* For sysctl proc_dointvec_minmax of i915_oa_max_sample_rate > * > - * 160ns is the smallest sampling period we can theoretically program the OA > - * unit with on Haswell, corresponding to 6.25MHz. > + * The highest sampling frequency we can theoretically program the OA unit > + * with is always half the timestamp frequency: E.g. 6.25Mhz for Haswell. > + * > + * Initialized just before we register the sysctl parameter. > */ > -static int oa_sample_rate_hard_limit = 6250000; > +static int oa_sample_rate_hard_limit; > > /* Theoretically we can program the OA unit to sample every 160ns but don't > * allow that by default unless root... > @@ -2549,6 +2551,12 @@ i915_perf_open_ioctl_locked(struct drm_i915_private *dev_priv, > return ret; > } > > +static u64 oa_exponent_to_ns(struct drm_i915_private *dev_priv, int exponent) > +{ > + return div_u64(1000000000ULL * (2ULL << exponent), > + dev_priv->perf.oa.timestamp_frequency); > +} > + > /** > * read_properties_unlocked - validate + copy userspace stream open properties > * @dev_priv: i915 device instance > @@ -2647,14 +2655,9 @@ static int read_properties_unlocked(struct drm_i915_private *dev_priv, > /* Theoretically we can program the OA unit to sample > * every 160ns but don't allow that by default unless </div></div>hmm, that's not actually true if we consider BXT, right? </blockquote><div> </div><div>right, I've updated this comment now. </div><div> </div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"> Reviewed-by: Matthew Auld <<a href="mailto:matthew.auld@intel.com">matthew.auld@intel.com</a>> </blockquote></div> </div><div class="gmail_extra">thanks </div></div>