On Wed, 2018-10-24 at 15:08 -0700, Dhinakaran Pandiyan wrote:
> On Sat, 2018-10-20 at 00:12 +0000, Souza, Jose wrote:
> > On Fri, 2018-10-19 at 16:14 -0700, Dhinakaran Pandiyan wrote:
> > > On Wed, 2018-10-10 at 17:41 -0700, José Roberto de Souza wrote:
> > > > While PSR is active hardware will do aux transactions by it
> > > > self
> > > > to
> > > > wakeup sink to receive a new frame when necessary. If that
> > > > transaction is not acked by sink, hardware will trigger this
> > > > interruption.
> > > >
> > > > So let's disable PSR as it is a hint that there is problem with
> > > > this
> > > > sink.
> > > >
> > > > The removed FIXME was asking to manually train the link but we
> > > > don't
> > > > need to do that as by spec sink should do a short pulse when it
> > > > is
> > > > out of sync with source, we just need to make sure it is awaken
> > > > and
> > > > the SDP header with PSR disable will trigger this condition.
> > > >
> > > > Cc: Dhinakaran Pandiyan <dhinakaran.pandi...@intel.com>
> > > > Signed-off-by: José Roberto de Souza <jose.so...@intel.com>
> > > > ---
> > > > drivers/gpu/drm/i915/i915_drv.h | 1 +
> > > > drivers/gpu/drm/i915/intel_psr.c | 39
> > > > ++++++++++++++++++++++++++++
> > > > ----
> > > > 2 files changed, 36 insertions(+), 4 deletions(-)
> > > >
> > > > diff --git a/drivers/gpu/drm/i915/i915_drv.h
> > > > b/drivers/gpu/drm/i915/i915_drv.h
> > > > index 3017ef037fed..e8ba00dd2c51 100644
> > > > --- a/drivers/gpu/drm/i915/i915_drv.h
> > > > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > > > @@ -638,6 +638,7 @@ struct i915_psr {
> > > > u8 sink_sync_latency;
> > > > ktime_t last_entry_attempt;
> > > > ktime_t last_exit;
> > > > + u32 irq_aux_error;
> > > > };
> > > >
> > > > enum intel_pch {
> > > > diff --git a/drivers/gpu/drm/i915/intel_psr.c
> > > > b/drivers/gpu/drm/i915/intel_psr.c
> > > > index 70d4e26e17b5..ad09130cb4ad 100644
> > > > --- a/drivers/gpu/drm/i915/intel_psr.c
> > > > +++ b/drivers/gpu/drm/i915/intel_psr.c
> > > > @@ -159,10 +159,16 @@ void intel_psr_irq_handler(struct
> > > > drm_i915_private *dev_priv, u32 psr_iir)
> > > > BIT(TRANSCODER_C);
> > > >
> > > > for_each_cpu_transcoder_masked(dev_priv,
> > > > cpu_transcoder,
> > > > transcoders) {
> > > > - /* FIXME: Exit PSR and link train manually when
> > > > this
> > > > happens. */
> > > > - if (psr_iir & EDP_PSR_ERROR(cpu_transcoder))
> > > > - DRM_DEBUG_KMS("[transcoder %s] PSR aux
> > > > error\n",
> > > > - transcoder_name(cpu_trans
> > > > coder));
> > > > + if (psr_iir & EDP_PSR_ERROR(cpu_transcoder)) {
> > > > + DRM_WARN("[transcoder %s] PSR aux
> > > > error\n",
> > > > + transcoder_name(cpu_transcoder
> > > > ));
> > >
> > > Downgrade this to debug since the error is handled in the
> > > driver?
> >
> > I think is better keep as DRM_WARN so it is shown in regular kernel
> > logs this way if a user opens a bug complaning why PSR is disabled
> > we
> > can check that is because of PSR aux error.
> >
> > >
> > > > +
> > > > + spin_lock(&dev_priv->irq_lock);
>
> This lock isn't needed either. How about setting a bool only if the
> transcoder is eDP and then scheduling a disable.
>
> > > > + dev_priv->psr.irq_aux_error |=
> > > > BIT(cpu_transcoder);
> > >
> > > Just ignore the non eDP bits, I don't think we want to do
> > > anything
> > > with
> > > the information that some other bit was set.
> > >
> > > > + spin_unlock(&dev_priv->irq_lock);
> > > > +
> > > > + schedule_work(&dev_priv->psr.work);
> > > > + }
> > > >
> > > > if (psr_iir &
> > > > EDP_PSR_PRE_ENTRY(cpu_transcoder)) {
> > > > dev_priv->psr.last_entry_attempt =
> > > > time_ns;
> > > > @@ -893,11 +899,36 @@ int intel_psr_set_debugfs_mode(struct
> > > > drm_i915_private *dev_priv,
> > > > return ret;
> > > > }
> > > >
> > > > +static void intel_psr_handle_irq(struct drm_i915_private
> > > > *dev_priv)
> > > > +{
> > > > + struct i915_psr *psr = &dev_priv->psr;
> > > > + u32 irq_aux_error;
> > > > +
> > > > + spin_lock_irq(&dev_priv->irq_lock);
> > > > + irq_aux_error = psr->irq_aux_error;
> > > > + psr->irq_aux_error = 0;
> > >
> > > A subsequent modeset will enable PSR again. I don't expect a
> > > modeset
> > > to
> > > to be able to fix an AUX wake up failure, so might as well
> > > disable
> > > it
> > > for good.
> >
> > Add another field to do that or set sink_support=false? I guess PSR
> > short pulses errors should also disable it good too?
>
> Reusing sink_support will get confusing, particularly because it is
> exposed in debugfs.
>
> >
> > >
> > > > + spin_unlock_irq(&dev_priv->irq_lock);
> > > > +
> > > > + /* right now PSR is only enabled in eDP */
> > >
> > > "right now" implies that PSR could be enabled for non eDP ports,
> > > but
> > > that's not the case.
> > >
> > >
> > > > + WARN_ON(irq_aux_error & ~BIT(TRANSCODER_EDP));
> > >
> > > This should go away if you ignore non-EDP bits, and a stack trace
> > > isn't
> > > particularly useful anyway.
> >
> > Okay I will remove this handlings for other transcoders.
> >
> > >
> > > > +
> > > > + mutex_lock(&psr->lock);
> > >
> > > Is this sufficient? Don't we have to serialize against ongoing
> > > modesets
> > > like we do for debugfs enable/disable. The disable sequence in
> > > bspec
> > > calls out a running pipe and port as pre-requisites.
> >
> > HW will only send a aux transaction when exiting PSR, in this cases
> > pipe will always be running:
>
> Sure, but psr_work() can run after the pipe is disabled.
>
> However, psr.enabled should take care of not writing to PSR_CTL if
> the
> pipe was already disabled. The question now is if we were in the
> middle
> of a modeset, disabling PSR here would have no effect if encoders are
> enabled after this point.
>
Another issue is the wait for idle under psr.lock, not a good idea to
have modesets waiting for that lock.
>
> > - exiting because of changes in the screen
> > - exiting because pipe will be disabled
> > - exiting because of PSR error
> >
> > >
> > > Ccing Ville and Maarten to get their opinion on this.
> > >
> > > > +
> > > > + intel_psr_disable_locked(psr->dp);
> > > > + /* let's make sure that sink is awaken */
> > > > + drm_dp_dpcd_writeb(&psr->dp->aux, DP_SET_POWER,
> > > > DP_SET_POWER_D0);
> > >
> > > Given that the hardware initiated AUX write failed, I would
> > > recommend
> > > reading back the sink PSR status to make sure disable worked.
> >
> > And in case of reading error or the value is not set try again?
> > This
> > could fall into a infite loop. intel_dp_aux_xfer() already try to
> > do
> > the transaction 5 times I guess if if failed the sink crashed and
> > there
> > is no recover.
> >
>
> I was thinking of printing an error here so that we know error
> recovery
> did not work.
>
>
> > >
> > > > +
> > > > + mutex_unlock(&dev_priv->psr.lock);
> > > > +}
> > > > +
> > > > static void intel_psr_work(struct work_struct *work)
> > > > {
> > > > struct drm_i915_private *dev_priv =
> > > > container_of(work, typeof(*dev_priv),
> > > > psr.work);
> > > >
> > > > + if (READ_ONCE(dev_priv->psr.irq_aux_error))
> > > > + intel_psr_handle_irq(dev_priv);
>
> Why not create a new work item for disable? I don't see why
> intel_psr_work() needs to be reused for a completely different
> reason.
>
> > >
> > > If psr_work() was already executing and past this check,
> > > schedule_work() in intel_psr_irq_handler will return a failure
> > > and
> > > disable PSR would now depend on getting an invalidate and flush
> > > operation. We should disable PSR without any dependency on flush
> > > or
> > > invalidate.
> >
> > For what I checked in the schedule_work() code if the work is
> > running
> > and there is a call to schedule_work() it will be schedule again.
> >
>
> From the documentation,
> /**
> * schedule_work - put work task in global workqueue
> * @work: job to be done
> *
> * Returns %false if @work was already on the kernel-global workqueue
> and
> * %true otherwise.
> *
>
> > >
> > >
> > > > +
> > > > mutex_lock(&dev_priv->psr.lock);
> > > >
> > > > if (!dev_priv->psr.enabled)
> >
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
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