[Intel-gfx] [PATCH 09/15] drm/i915/guc: Move check for fast memcpy_wc to relay creation

[Chris Wilson]

Quoting Michał Winiarski (2018-02-27 15:37:04)
> On Tue, Feb 27, 2018 at 03:37:25PM +0100, Michal Wajdeczko wrote:
> > On Tue, 27 Feb 2018 13:52:24 +0100, Michał Winiarski
> > <michal.winiarski at intel.com> wrote:
> > 
> > > We only need those fast memcpy_wc when we're using relay to read
> > > continuous GuC log. Let's prevent the user from creating a relay if we
> > > know we won't be able to keep up with GuC.
> > > 
> > > Signed-off-by: Michał Winiarski <michal.winiarski at intel.com>
> > > Cc: Chris Wilson <chris at chris-wilson.co.uk>
> > > Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> > > Cc: Sagar Arun Kamble <sagar.a.kamble at intel.com>
> > > Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
> > > ---
> > >  drivers/gpu/drm/i915/intel_guc_log.c | 20 ++++++++++----------
> > >  1 file changed, 10 insertions(+), 10 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/i915/intel_guc_log.c
> > > b/drivers/gpu/drm/i915/intel_guc_log.c
> > > index 4dee65692f5f..d2aca10ab986 100644
> > > --- a/drivers/gpu/drm/i915/intel_guc_log.c
> > > +++ b/drivers/gpu/drm/i915/intel_guc_log.c
> > > @@ -452,16 +452,6 @@ int intel_guc_log_create(struct intel_guc *guc)
> > >     GEM_BUG_ON(guc->log.vma);
> > > -   /*
> > > -    * We require SSE 4.1 for fast reads from the GuC log buffer and
> > > -    * it should be present on the chipsets supporting GuC based
> > > -    * submisssions.
> > > -    */
> > > -   if (WARN_ON(!i915_has_memcpy_from_wc())) {
> > > -           ret = -EINVAL;
> > > -           goto err;
> > > -   }
> > > -
> > >     vma = intel_guc_allocate_vma(guc, GUC_LOG_SIZE);
> > >     if (IS_ERR(vma)) {
> > >             ret = PTR_ERR(vma);
> > > @@ -568,6 +558,16 @@ int intel_guc_log_relay_open(struct intel_guc *guc)
> > >             goto out_unlock;
> > >     }
> > > +   /*
> > > +    * We require SSE 4.1 for fast reads from the GuC log buffer and
> > > +    * it should be present on the chipsets supporting GuC based
> > > +    * submisssions.
> > > +    */
> > > +   if (!i915_has_memcpy_from_wc()) {
> > > +           ret = -EINVAL;
> > 
> > hmm, maybe -ENODEV as this is not user fault
> 
> ENODEV means that we're not using GuC.
> -ENXIO?

Do we respond to the error at all? It should just result in the relay
not being available, right?

(i.e. are we just discussing the color of the bikeshed :)
-Chris