Re: [PATCH v5 3/4] drm/xe/migrate: Clear CCS when clearing bo on xe2

[Matthew Auld <matthew.auld@intel.com>]

On 04/07/2024 09:18, Nirmoy Das wrote:
> Clearing bo with uncompress PTE will trigger a CCS clearing as well
> for XE2, so skip emit_copy_ccs() when on xe2 when clearing bo.
> 
> v2: When clearing BO, CCS clear happens with all command as long
>      as PTEs are uncompress.
> 
> Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: "Thomas Hellström" <thomas.hellstrom@linux.intel.com>
> Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_migrate.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_migrate.c b/drivers/gpu/drm/xe/xe_migrate.c
> index e0a3f6921572..cc8beed2bf8e 100644
> --- a/drivers/gpu/drm/xe/xe_migrate.c
> +++ b/drivers/gpu/drm/xe/xe_migrate.c
> @@ -1061,7 +1061,8 @@ struct dma_fence *xe_migrate_clear(struct xe_migrate *m,
>   		if (clear_vram && xe_migrate_allow_identity(clear_L0, &src_it))
>   			xe_res_next(&src_it, clear_L0);
>   		else
> -			emit_pte(m, bb, clear_L0_pt, clear_vram, clear_ccs,
> +			/* Use uncompressed pte so clear happens in the real memory. */
> +			emit_pte(m, bb, clear_L0_pt, clear_vram, false,
>   				 &src_it, clear_L0, dst);

I assume this uses coherency 1way+ mode for that pat index? We could 
potentially use coh_none instead, for the case where bo.cpu_caching != 
wb. In theory that should be faster, but could be ignored for now.

>   
>   		bb->cs[bb->len++] = MI_BATCH_BUFFER_END;
> @@ -1070,7 +1071,9 @@ struct dma_fence *xe_migrate_clear(struct xe_migrate *m,
>   		if (clear_bo_data)
>   			emit_clear(gt, bb, clear_L0_ofs, clear_L0, XE_PAGE_SIZE, clear_vram);
>   
> -		if (xe_device_has_flat_ccs(xe)) {
> +		/* Clearing BO with uncompress PTE will clear CCS metadata as well on XE2 */
> +		if (xe_device_has_flat_ccs(xe) && clear_ccs &&
> +		    !(clear_bo_data && GRAPHICS_VERx100(gt_to_xe(gt)) >= 2000)) {
>   			emit_copy_ccs(gt, bb, clear_L0_ofs, true,
>   				      m->cleared_mem_ofs, false, clear_L0);
>   			flush_flags = MI_FLUSH_DW_CCS;