Re: [PATCH 05/11] drm/i915/dsb: add intel_dsb_gosub_finish()

["Ville Syrjälä" <ville.syrjala@linux.intel.com>]

On Mon, Apr 07, 2025 at 07:53:53PM +0530, Chaitanya Kumar Borah wrote:
> A DSB buffer which will be used for GOSUB execution does not need
> the DEWAKE mechanism but still need to be 64 bit aligned. Add helper
> to finish preparation of a dsb buffer to be executed with GOSUB
> instruction.
> 
> Signed-off-by: Chaitanya Kumar Borah <chaitanya.kumar.borah@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dsb.c | 7 +++++++
>  drivers/gpu/drm/i915/display/intel_dsb.h | 1 +
>  2 files changed, 8 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dsb.c b/drivers/gpu/drm/i915/display/intel_dsb.c
> index 2cda6fc7857b..bffa02a0442c 100644
> --- a/drivers/gpu/drm/i915/display/intel_dsb.c
> +++ b/drivers/gpu/drm/i915/display/intel_dsb.c
> @@ -585,6 +585,13 @@ void intel_dsb_gosub(struct intel_dsb *dsb,
>  	intel_dsb_align_tail(dsb);
>  }
>  
> +void intel_dsb_gosub_finish(struct intel_dsb *dsb)
> +{
> +	intel_dsb_align_tail(dsb);

There is one more w/a listd that may require us to do something like::

/* "All subroutines called by the GOSUB instruction must end with a cacheline of NOPs" */
intel_dsb_noop(8);

> +
> +	intel_dsb_buffer_flush_map(&dsb->dsb_buf);
> +}
> +
>  void intel_dsb_finish(struct intel_dsb *dsb)
>  {
>  	struct intel_crtc *crtc = dsb->crtc;
> diff --git a/drivers/gpu/drm/i915/display/intel_dsb.h b/drivers/gpu/drm/i915/display/intel_dsb.h
> index 8b2cf0a7b7e6..6900acd603b8 100644
> --- a/drivers/gpu/drm/i915/display/intel_dsb.h
> +++ b/drivers/gpu/drm/i915/display/intel_dsb.h
> @@ -31,6 +31,7 @@ struct intel_dsb *intel_dsb_prepare(struct intel_atomic_state *state,
>  				    enum intel_dsb_id dsb_id,
>  				    unsigned int max_cmds);
>  void intel_dsb_finish(struct intel_dsb *dsb);
> +void intel_dsb_gosub_finish(struct intel_dsb *dsb);
>  void intel_dsb_cleanup(struct intel_dsb *dsb);
>  void intel_dsb_reg_write(struct intel_dsb *dsb,
>  			 i915_reg_t reg, u32 val);
> -- 
> 2.25.1

-- 
Ville Syrjälä
Intel