Re: [PATCH v5 1/4] drm/xe/lrc: Add xe lrc ring tail function definitions

[Matthew Brost <matthew.brost@intel.com>]

On Mon, Apr 15, 2024 at 01:31:32PM -0600, Summers, Stuart wrote:
> On Mon, 2024-04-15 at 11:46 -0700, Jonathan Cavitt wrote:
> > Add defintions for the functions xe_lrc_set_ring_tail and
> > xe_lrc_ring_tail to match the definitions for xe_lrc_set_ring_head
> > and
> > xe_lrc_ring_head, respectively, except tarting the lrc tail.
> > 
> > Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
> > CC: Niranjana Vishwanathapura <niranjana.vishwanathapura@intel.com>
> > CC: Brian Welty <brian.welty@intel.com>
> > CC: Matt Roper <matthew.d.roper@intel.com>
> > ---
> >  drivers/gpu/drm/xe/xe_lrc.c | 10 ++++++++++
> >  drivers/gpu/drm/xe/xe_lrc.h |  2 ++
> >  2 files changed, 12 insertions(+)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_lrc.c
> > b/drivers/gpu/drm/xe/xe_lrc.c
> > index 615bbc372ac62..e91ecbcceba5c 100644
> > --- a/drivers/gpu/drm/xe/xe_lrc.c
> > +++ b/drivers/gpu/drm/xe/xe_lrc.c
> > @@ -834,6 +834,16 @@ void xe_lrc_finish(struct xe_lrc *lrc)
> >         xe_bo_put(lrc->bo);
> >  }
> >  
> > +void xe_lrc_set_ring_tail(struct xe_lrc *lrc, u32 tail)
> > +{
> > +       xe_lrc_write_ctx_reg(lrc, CTX_RING_TAIL, tail);
> > +}
> > +
> > +u32 xe_lrc_ring_tail(struct xe_lrc *lrc)
> > +{
> > +       return xe_lrc_read_ctx_reg(lrc, CTX_RING_TAIL) & TAIL_ADDR;
> > +}
> > +
> >  void xe_lrc_set_ring_head(struct xe_lrc *lrc, u32 head)
> >  {
> 
> I see lower in xe_lrc.c we're doing this (xe_lrc_snapshot_capture):
> snapshot->tail.memory = xe_lrc_read_ctx_reg(lrc, CTX_RING_TAIL);
> 
> Should we change this call to use the new wrapper also?
> 

Yea. Also xe_guc_submit.c sets the LRC tail. It should be updated to use
the helper too.

Matt

> Thanks,
> Stuart
> 
> >         xe_lrc_write_ctx_reg(lrc, CTX_RING_HEAD, head);
> > diff --git a/drivers/gpu/drm/xe/xe_lrc.h
> > b/drivers/gpu/drm/xe/xe_lrc.h
> > index d32fa31faa2cf..f355b0eeb5658 100644
> > --- a/drivers/gpu/drm/xe/xe_lrc.h
> > +++ b/drivers/gpu/drm/xe/xe_lrc.h
> > @@ -24,6 +24,8 @@ void xe_lrc_finish(struct xe_lrc *lrc);
> >  size_t xe_lrc_size(struct xe_device *xe, enum xe_engine_class
> > class);
> >  u32 xe_lrc_pphwsp_offset(struct xe_lrc *lrc);
> >  
> > +void xe_lrc_set_ring_tail(struct xe_lrc *lrc, u32 tail);
> > +u32 xe_lrc_ring_tail(struct xe_lrc *lrc);
> >  void xe_lrc_set_ring_head(struct xe_lrc *lrc, u32 head);
> >  u32 xe_lrc_ring_head(struct xe_lrc *lrc);
> >  u32 xe_lrc_ring_space(struct xe_lrc *lrc);
>