[Intel-gfx] [PATCH 04/12] drm/i915/execlists: Refactor CSB state machine

[Chris Wilson]

Quoting Mika Kuoppala (2019-07-01 12:49:48)
> Chris Wilson <chris at chris-wilson.co.uk> writes:
> 
> > Daniele pointed out that the CSB status information will change with
> > Tigerlake and suggested that we could rearrange our state machine to
> > hide the differences in generation. gcc also prefers the explicit state
> > machine, so make it so:
> >
> > process_csb                                 1980    1967     -13
> >
> > Suggested-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
> > Cc: Tvrtko Ursulin <tvrtko.ursulin at linux.intel.com>
> > Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>
> > ---
> >  drivers/gpu/drm/i915/gt/intel_lrc.c | 64 ++++++++++++++++++++---------
> >  1 file changed, 44 insertions(+), 20 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
> > index 471e134de186..953b3938a85f 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> > @@ -1279,6 +1279,30 @@ reset_in_progress(const struct intel_engine_execlists *execlists)
> >       return unlikely(!__tasklet_is_enabled(&execlists->tasklet));
> >  }
> >  
> > +enum csb_step {
> > +     CSB_NOP,
> > +     CSB_PROMOTE,
> > +     CSB_PREEMPT,
> > +     CSB_COMPLETE,
> > +};
> > +
> > +static inline enum csb_step
> > +csb_parse(const struct intel_engine_execlists *execlists, const u32 *csb)
> > +{
> > +     unsigned int status = *csb;
> 
> Could be const u32 aswell (stylistic).

No need to specify here, local register is fine, so left it as natural.

> Just makes me ponder why you want to read csb in here
> and not in the callsite.

Whatever gcc prefers when there is multiple csb_parsers. :)
-Chris