[Intel-gfx] [PATCH 3/3] drm/i915: Enable GGTT blitting in MTL

[Zeng, Oak]

Thanks,
Oak

> -----Original Message-----
> From: Roper, Matthew D <matthew.d.roper at intel.com>
> Sent: August 24, 2023 11:54 AM
> To: Zeng, Oak <oak.zeng at intel.com>
> Cc: intel-gfx at lists.freedesktop.org; Shyti, Andi <andi.shyti at intel.com>;
> chris.p.wilson at linux.intel.com; Das, Nirmoy <nirmoy.das at intel.com>
> Subject: Re: [Intel-gfx] [PATCH 3/3] drm/i915: Enable GGTT blitting in MTL
> 
> On Tue, Aug 22, 2023 at 11:28:59AM -0400, Oak Zeng wrote:
> > From: Nirmoy Das <nirmoy.das at intel.com>
> >
> > MTL can hang because of a HW bug while parallel reading/writing
> > from/to LMEM/GTTMMADR BAR so try to reduce GGTT update
> > related pci transactions with blitter command as recommended
> > for Wa_22018444074.
> 
> Drive-by comment:  this isn't a valid workaround number.  22018444074 is
> a per-platform record number, whereas workarounds should always be
> identified by their cross-platform lineage number, which will stay
> constant if the workaround winds up extending to future platforms as
> well.  So in this case, the workaround should be referred to as
> Wa_13010847436.

Spoke with Matt offline. Will keep lineage number 13010847436. Also put a soc HSD number 14019519902

Thanks Matt for explanation!
Oak

> 
> 
> Matt
> 
> >
> > To issue blitter commands, the driver must be primed to receive
> > requests. Maintain blitter-based GGTT update disablement until driver
> > probing completes. Moreover, implement a temporary disablement
> > of blitter prior to entering suspend, followed by re-enablement
> > post-resume. This is acceptable as those transition periods are
> > mostly single threaded.
> >
> > v2: Disable GGTT blitter prior to runtime suspend and re-enable
> > after runtime resume. (Oak)
> >
> > Signed-off-by: Nirmoy Das <nirmoy.das at intel.com>
> > Signed-off-by: Oak Zeng <oak.zeng at intel.com>
> > ---
> >  drivers/gpu/drm/i915/i915_driver.c | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/i915_driver.c
> b/drivers/gpu/drm/i915/i915_driver.c
> > index f8dbee7a5af7..6afe0adc8ddb 100644
> > --- a/drivers/gpu/drm/i915/i915_driver.c
> > +++ b/drivers/gpu/drm/i915/i915_driver.c
> > @@ -815,6 +815,7 @@ int i915_driver_probe(struct pci_dev *pdev, const struct
> pci_device_id *ent)
> >  	i915_welcome_messages(i915);
> >
> >  	i915->do_release = true;
> > +	intel_engine_blitter_context_set_ready(to_gt(i915), true);
> >
> >  	return 0;
> >
> > @@ -855,6 +856,7 @@ void i915_driver_remove(struct drm_i915_private *i915)
> >  {
> >  	intel_wakeref_t wakeref;
> >
> > +	intel_engine_blitter_context_set_ready(to_gt(i915), false);
> >  	wakeref = intel_runtime_pm_get(&i915->runtime_pm);
> >
> >  	i915_driver_unregister(i915);
> > @@ -1077,6 +1079,8 @@ static int i915_drm_suspend(struct drm_device *dev)
> >  	struct pci_dev *pdev = to_pci_dev(dev_priv->drm.dev);
> >  	pci_power_t opregion_target_state;
> >
> > +	intel_engine_blitter_context_set_ready(to_gt(dev_priv), false);
> > +
> >  	disable_rpm_wakeref_asserts(&dev_priv->runtime_pm);
> >
> >  	/* We do a lot of poking in a lot of registers, make sure they work
> > @@ -1264,6 +1268,7 @@ static int i915_drm_resume(struct drm_device *dev)
> >  	intel_gvt_resume(dev_priv);
> >
> >  	enable_rpm_wakeref_asserts(&dev_priv->runtime_pm);
> > +	intel_engine_blitter_context_set_ready(to_gt(dev_priv), true);
> >
> >  	return 0;
> >  }
> > @@ -1515,6 +1520,7 @@ static int intel_runtime_suspend(struct device *kdev)
> >  	if (drm_WARN_ON_ONCE(&dev_priv-
> >drm, !HAS_RUNTIME_PM(dev_priv)))
> >  		return -ENODEV;
> >
> > +	intel_engine_blitter_context_set_ready(to_gt(dev_priv), false);
> >  	drm_dbg(&dev_priv->drm, "Suspending device\n");
> >
> >  	disable_rpm_wakeref_asserts(rpm);
> > @@ -1669,6 +1675,8 @@ static int intel_runtime_resume(struct device *kdev)
> >  	else
> >  		drm_dbg(&dev_priv->drm, "Device resumed\n");
> >
> > +	intel_engine_blitter_context_set_ready(to_gt(dev_priv), true);
> > +
> >  	return ret;
> >  }
> >
> > --
> > 2.26.3
> >
> 
> --
> Matt Roper
> Graphics Software Engineer
> Linux GPU Platform Enablement
> Intel Corporation