Re: [PATCH 6/6] drm/xe/migrate: skip bounce buffer path on xe2

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

On Wed, Oct 15, 2025 at 03:19:36PM +0100, Matthew Auld wrote:
> Now that we support MEM_COPY we should be able to use the PAGE_COPY
> mode, otherwise falling back to BYTE_COPY mode when we have odd
> sizing/alignment.
> 
> Signed-off-by: Matthew Auld <matthew.auld@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_migrate.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_migrate.c b/drivers/gpu/drm/xe/xe_migrate.c
> index da1fefb96070..8bd8e8179313 100644
> --- a/drivers/gpu/drm/xe/xe_migrate.c
> +++ b/drivers/gpu/drm/xe/xe_migrate.c
> @@ -1933,9 +1933,11 @@ static struct dma_fence *xe_migrate_vram(struct xe_migrate *m,
>  	int err;
>  	unsigned long i, j;
>  	bool use_pde = xe_migrate_vram_use_pde(sram_addr, len + sram_offset);
> +	bool has_byte_copy = GRAPHICS_VER(xe) >= 20;

See my comment in previous patch about maybe storing this in xe_device.info.

Whatever we land on there, absorb into this patch.

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

>  
> -	if (drm_WARN_ON(&xe->drm, (len & XE_CACHELINE_MASK) ||
> -			(sram_offset | vram_addr) & XE_CACHELINE_MASK))
> +	if (!has_byte_copy &&
> +	    drm_WARN_ON(&xe->drm,
> +			(len & XE_CACHELINE_MASK) || (sram_offset | vram_addr) & XE_CACHELINE_MASK))
>  		return ERR_PTR(-EOPNOTSUPP);
>  
>  	xe_assert(xe, npages * PAGE_SIZE <= MAX_PREEMPTDISABLE_TRANSFER);
> @@ -2149,13 +2151,14 @@ int xe_migrate_access_memory(struct xe_migrate *m, struct xe_bo *bo,
>  	struct drm_pagemap_addr *pagemap_addr;
>  	unsigned long page_offset = (unsigned long)buf & ~PAGE_MASK;
>  	int bytes_left = len, current_page = 0;
> +	bool has_byte_copy = GRAPHICS_VER(xe) >= 20;
>  	void *orig_buf = buf;
>  
>  	xe_bo_assert_held(bo);
>  
>  	/* Use bounce buffer for small access and unaligned access */
> -	if (!IS_ALIGNED(len, XE_CACHELINE_BYTES) ||
> -	    !IS_ALIGNED((unsigned long)buf + offset, XE_CACHELINE_BYTES)) {
> +	if (!has_byte_copy && (!IS_ALIGNED(len, XE_CACHELINE_BYTES) ||
> +			       !IS_ALIGNED((unsigned long)buf + offset, XE_CACHELINE_BYTES))) {
>  		int buf_offset = 0;
>  		void *bounce;
>  		int err;
> -- 
> 2.51.0
>