Re: [PATCH v5 5/7] drm/xe/lrc: Allow INDIRECT_CTX for more engine classes

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Tue, Sep 16, 2025 at 02:15:42PM -0700, Lucas De Marchi wrote:
> Currently it's only allowed for render and compute. Going forward we
> want to enable it for more engine classes. Let the XE_LRC_FLAG_INDIRECT_CTX
> flag (and thus gt_engine_needs_indirect_ctx()) be the deciding factor
> for its availability.
> 
> While at it, add the missing const to rcs_funcs array. Since
> CTX_INDIRECT_CTX_OFFSET_DEFAULT already matches the HW default and
> gt_engine_needs_indirect_ctx() only ever enables it for rcs/ccs, there
> is no change in behavior, it's only preparation for future use case.
> 

thanks for the offline explanation and pointers

Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>


> Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
> ---
>  drivers/gpu/drm/xe/regs/xe_lrc_layout.h |  3 ---
>  drivers/gpu/drm/xe/xe_lrc.c             | 14 ++++++++++----
>  2 files changed, 10 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/regs/xe_lrc_layout.h b/drivers/gpu/drm/xe/regs/xe_lrc_layout.h
> index 1b101edb838bf..b5eff383902c5 100644
> --- a/drivers/gpu/drm/xe/regs/xe_lrc_layout.h
> +++ b/drivers/gpu/drm/xe/regs/xe_lrc_layout.h
> @@ -40,7 +40,4 @@
>  #define INDIRECT_CTX_RING_START_UDW	(0x08 + 1)
>  #define INDIRECT_CTX_RING_CTL		(0x0a + 1)
>  
> -#define CTX_INDIRECT_CTX_OFFSET_MASK	REG_GENMASK(15, 6)
> -#define CTX_INDIRECT_CTX_OFFSET_DEFAULT	REG_FIELD_PREP(CTX_INDIRECT_CTX_OFFSET_MASK, 0xd)
> -
>  #endif
> diff --git a/drivers/gpu/drm/xe/xe_lrc.c b/drivers/gpu/drm/xe/xe_lrc.c
> index c706585611d55..0ab99c210d882 100644
> --- a/drivers/gpu/drm/xe/xe_lrc.c
> +++ b/drivers/gpu/drm/xe/xe_lrc.c
> @@ -1281,9 +1281,11 @@ static int setup_wa_bb(struct xe_lrc *lrc, struct xe_hw_engine *hwe)
>  static int
>  setup_indirect_ctx(struct xe_lrc *lrc, struct xe_hw_engine *hwe)
>  {
> -	static struct bo_setup rcs_funcs[] = {
> +	static const struct bo_setup rcs_funcs[] = {
>  		{ .setup = setup_timestamp_wa },
>  	};
> +	static const struct bo_setup xcs_funcs[] = {
> +	};
>  	struct bo_setup_state state = {
>  		.lrc = lrc,
>  		.hwe = hwe,
> @@ -1300,6 +1302,9 @@ setup_indirect_ctx(struct xe_lrc *lrc, struct xe_hw_engine *hwe)
>  	    hwe->class == XE_ENGINE_CLASS_COMPUTE) {
>  		state.funcs = rcs_funcs;
>  		state.num_funcs = ARRAY_SIZE(rcs_funcs);
> +	} else {
> +		state.funcs = xcs_funcs;
> +		state.num_funcs = ARRAY_SIZE(xcs_funcs);
>  	}
>  
>  	if (xe_gt_WARN_ON(lrc->gt, !state.funcs))
> @@ -1326,14 +1331,15 @@ setup_indirect_ctx(struct xe_lrc *lrc, struct xe_hw_engine *hwe)
>  	finish_bo(&state);
>  	kfree(state.buffer);
>  
> +	/*
> +	 * Enable INDIRECT_CTX leaving INDIRECT_CTX_OFFSET at its default: it
> +	 * varies per engine class, but the default is good enough
> +	 */
>  	xe_lrc_write_ctx_reg(lrc,
>  			     CTX_CS_INDIRECT_CTX,
>  			     (xe_bo_ggtt_addr(lrc->bo) + state.offset) |
>  			     /* Size in CLs. */
>  			     (state.written * sizeof(u32) / 64));
> -	xe_lrc_write_ctx_reg(lrc,
> -			     CTX_CS_INDIRECT_CTX_OFFSET,
> -			     CTX_INDIRECT_CTX_OFFSET_DEFAULT);
>  
>  	return 0;
>  }
> 
> -- 
> 2.50.1
>