Re: [PATCH v6] drm/i915/guc: Add support for reset engine using GuC commands

[Jeff McGee <jeff.mcgee@intel.com>]

On Wed, Nov 01, 2017 at 01:58:04PM +0000, Chris Wilson wrote:
> Quoting Michel Thierry (2017-10-31 22:53:09)
> > This patch adds per engine reset and recovery (TDR) support when GuC is
> > used to submit workloads to GPU.
> > 
> > In the case of i915 directly submission to ELSP, driver manages hang
> > detection, recovery and resubmission. With GuC submission these tasks
> > are shared between driver and GuC. i915 is still responsible for detecting
> > a hang, and when it does it only requests GuC to reset that Engine. GuC
> > internally manages acquiring forcewake and idling the engine before
> > resetting it.
> > 
> > Once the reset is successful, i915 takes over again and handles the
> > resubmission. The scheduler in i915 knows which requests are pending so
> > after resetting a engine, pending workloads/requests are resubmitted
> > again.
> > 
> > v2: s/i915_guc_request_engine_reset/i915_guc_reset_engine/ to match the
> > non-guc function names.
> > 
> > v3: Removed debug message about engine restarting from which request,
> > since the new baseline do it regardless of submission mode. (Chris)
> > 
> > v4: Rebase.
> > 
> > v5: Do not pass unnecessary reporting flags to the fw (Jeff);
> > tasklet_schedule(&execlists->irq_tasklet) handles the resubmit; rebase.
> > 
> > v6: Rename the existing reset engine function and share a similar
> > interface between guc and non-guc paths (Chris).
> > 
> > Signed-off-by: Michel Thierry <michel.thierry@intel.com>
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > ---
> >  drivers/gpu/drm/i915/i915_drv.c       | 15 +++++++++++++--
> >  drivers/gpu/drm/i915/i915_drv.h       |  2 ++
> >  drivers/gpu/drm/i915/intel_guc.c      | 24 ++++++++++++++++++++++++
> >  drivers/gpu/drm/i915/intel_guc_fwif.h |  1 +
> >  drivers/gpu/drm/i915/intel_uncore.c   |  5 -----
> >  5 files changed, 40 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
> > index af745749509c..359333a423cf 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.c
> > +++ b/drivers/gpu/drm/i915/i915_drv.c
> > @@ -1950,6 +1950,12 @@ void i915_reset(struct drm_i915_private *i915, unsigned int flags)
> >         goto finish;
> >  }
> >  
> > +static inline int intel_gt_reset_engine(struct drm_i915_private *dev_priv,
> > +                                       struct intel_engine_cs *engine)
> > +{
> > +       return intel_gpu_reset(dev_priv, intel_engine_flag(engine));
> > +}
> > +
> >  /**
> >   * i915_reset_engine - reset GPU engine to recover from a hang
> >   * @engine: engine to reset
> > @@ -1984,10 +1990,15 @@ int i915_reset_engine(struct intel_engine_cs *engine, unsigned int flags)
> >                 goto out;
> >         }
> >  
> > -       ret = intel_gpu_reset(engine->i915, intel_engine_flag(engine));
> > +       if (!engine->i915->guc.execbuf_client)
> > +               ret = intel_gt_reset_engine(engine->i915, engine);
> > +       else
> > +               ret = intel_guc_reset_engine(&engine->i915->guc, engine);
> > +
> >         if (ret) {
> >                 /* If we fail here, we expect to fallback to a global reset */
> > -               DRM_DEBUG_DRIVER("Failed to reset %s, ret=%d\n",
> > +               DRM_DEBUG_DRIVER("%sFailed to reset %s, ret=%d\n",
> > +                                (engine->i915->guc.execbuf_client ? "GUC ":""),
> 
> A bit overkill on the parentheses there ;)
> 
> Lgtm, can you please ping, say, Jeff or Daniele for an r-b on the guc
> interaction?
> -Chris

There is one small change needed in the GuC preemption protocol to make it
compatible with GuC engine reset. I will send that shortly.

There are also a couple of corner case bugs with engine reset in our current
firmware versions. We are planning a firmware update to address those. But
the host-side code here is fine. So...

Reviewed-by: Jeff McGee <jeff.mcgee@intel.com>
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