On Fri, Jan 08, 2021 at 11:38:04AM +0200, Jani Nikula wrote: > On Thu, 07 Jan 2021, Anshuman Gupta <[email protected]> wrote: > > We need a power_domain wakeref in pps_{lock,unlock} to prevent > > a race while resetting pps state in intel_power_sequencer_reset(). > > > > intel_power_sequencer_reset() need a pps_mutex to access pps_pipe > > but it can't grab pps_mutex due to deadlock with power_well > > functions are called while holding pps_mutex. > > intel_power_sequencer_reset() is called by power_well function > > associated with legacy platforms like vlv and chv therefore re-use > > the POWER_DOMAIN_DISPLAY_CORE power domain, which only used > > by vlv and chv display power domain. > > > > This will avoids the unnecessary noise of unrelated power wells > > in pps_{lock,unlock}. > > > > Cc: Jani Nikula <[email protected]> > > Cc: Imre Deak <[email protected]> > > Signed-off-by: Anshuman Gupta <[email protected]> > > Imre convinced me yesterday on irc that this should work. > > Reviewed-by: Jani Nikula <[email protected]> > > On the surface, this reduces the need to enable/disable the aux power so > much. It's unnecessary, so it stands to reason to optimize it. We should > only grab the domain references we actually need. > > However, this *also* papers over an issue we've been seeing [1]. We need > to be aware the root cause for that remains unknown, and needs to be > figured out. > > I presume simply doing aux transfers won't reproduce the problem, > because that disables the power asynchronously since commit f39194a7a8b9 > ("drm/i915: Disable power asynchronously during DP AUX > transfers"). Perhaps we wouldn't have seen this at all if pps_unlock() > also did that as suggested in the commit message. > > Anyway, I'd like to get acks or rb's from Imre and Ville before merging > this.
Looks ok to me: Acked-by: Imre Deak <[email protected]> > > > BR, > Jani. > > > [1] http://lore.kernel.org/r/[email protected] > > > > --- > > drivers/gpu/drm/i915/display/intel_dp.c | 8 ++------ > > 1 file changed, 2 insertions(+), 6 deletions(-) > > > > diff --git a/drivers/gpu/drm/i915/display/intel_dp.c > > b/drivers/gpu/drm/i915/display/intel_dp.c > > index 8a00e609085f..4f190a82d4ad 100644 > > --- a/drivers/gpu/drm/i915/display/intel_dp.c > > +++ b/drivers/gpu/drm/i915/display/intel_dp.c > > @@ -895,9 +895,7 @@ pps_lock(struct intel_dp *intel_dp) > > * See intel_power_sequencer_reset() why we need > > * a power domain reference here. > > */ > > - wakeref = intel_display_power_get(dev_priv, > > - > > intel_aux_power_domain(dp_to_dig_port(intel_dp))); > > - > > + wakeref = intel_display_power_get(dev_priv, POWER_DOMAIN_DISPLAY_CORE); > > mutex_lock(&dev_priv->pps_mutex); > > > > return wakeref; > > @@ -909,9 +907,7 @@ pps_unlock(struct intel_dp *intel_dp, intel_wakeref_t > > wakeref) > > struct drm_i915_private *dev_priv = dp_to_i915(intel_dp); > > > > mutex_unlock(&dev_priv->pps_mutex); > > - intel_display_power_put(dev_priv, > > - > > intel_aux_power_domain(dp_to_dig_port(intel_dp)), > > - wakeref); > > + intel_display_power_put(dev_priv, POWER_DOMAIN_DISPLAY_CORE, wakeref); > > return 0; > > } > > -- > Jani Nikula, Intel Open Source Graphics Center _______________________________________________ Intel-gfx mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/intel-gfx
