Re: [PATCH 4/6] drm/xe/migrate: trim batch buffer sizing

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

On Wed, Oct 15, 2025 at 03:19:34PM +0100, Matthew Auld wrote:
> We have an extra two dwords, but it looks like we should only need one
> for the extra bb_end. Likely this is just leftover from back when the
> arb handling was moved into the ring programming.
> 
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>

Reviewed-by: Matthew Brost <matthew.brost@intel.com>

> ---
>  drivers/gpu/drm/xe/xe_migrate.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_migrate.c b/drivers/gpu/drm/xe/xe_migrate.c
> index 6b6caeb5cdc6..3801152b7f8f 100644
> --- a/drivers/gpu/drm/xe/xe_migrate.c
> +++ b/drivers/gpu/drm/xe/xe_migrate.c
> @@ -847,7 +847,7 @@ struct dma_fence *xe_migrate_copy(struct xe_migrate *m,
>  				&ccs_it);
>  
>  	while (size) {
> -		u32 batch_size = 2; /* arb_clear() + MI_BATCH_BUFFER_END */
> +		u32 batch_size = 1; /* MI_BATCH_BUFFER_END */
>  		struct xe_sched_job *job;
>  		struct xe_bb *bb;
>  		u32 flush_flags = 0;
> @@ -1312,7 +1312,7 @@ struct dma_fence *xe_migrate_clear(struct xe_migrate *m,
>  
>  		/* Calculate final sizes and batch size.. */
>  		pte_flags = clear_vram ? PTE_UPDATE_FLAG_IS_VRAM : 0;
> -		batch_size = 2 +
> +		batch_size = 1 +
>  			pte_update_size(m, pte_flags, src, &src_it,
>  					&clear_L0, &clear_L0_ofs, &clear_L0_pt,
>  					clear_bo_data ? emit_clear_cmd_len(gt) : 0, 0,
> @@ -1876,7 +1876,7 @@ static struct dma_fence *xe_migrate_vram(struct xe_migrate *m,
>  	struct xe_device *xe = gt_to_xe(gt);
>  	bool use_usm_batch = xe->info.has_usm;
>  	struct dma_fence *fence = NULL;
> -	u32 batch_size = 2;
> +	u32 batch_size = 1;
>  	u64 src_L0_ofs, dst_L0_ofs;
>  	struct xe_sched_job *job;
>  	struct xe_bb *bb;
> -- 
> 2.51.0
>