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

["Summers, Stuart" <stuart.summers@intel.com>]

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?

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);