Re: [PATCH v3 02/33] drm/ttm/pool: Add ttm_pool_page_order_nodma() helper

[Matthew Auld]

On 11/07/2026 03:55, Matthew Brost wrote:
> TTM records the allocation order of a multi-order page in page->private at
> allocation time. For pools that do not use dma_alloc the order is stored
> directly, while dma_alloc pools store a struct ttm_pool_dma pointer there
> instead. Drivers that do their own DMA mapping (e.g. Xe) need the per-page
> order to walk a populated ttm_tt one chunk at a time, but cannot rely on
> folio_order(): TTM allocates high-order pages with alloc_pages_node()
> without __GFP_COMP, so they are not compound and folio_order() always
> returns 0.
>
> Expose ttm_pool_page_order_nodma(), a thin wrapper that returns the order
> recorded in page->private. It is only valid for pages from a pool that does
> not use dma_alloc; whether a TTM device uses dma_alloc is fixed at ttm
> device init time, so callers know from their device configuration that this
> helper applies. Use it from the existing internal ttm_pool_page_order() to
> keep a single source of truth.
>
> Cc: Carlos Santa <carlos.santa@xxxxxxxxx>
> Cc: Ryan Neph <ryanneph@xxxxxxxxxx>
> Cc: Christian Koenig <christian.koenig@xxxxxxx>
> Cc: Huang Rui <ray.huang@xxxxxxx>
> Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> Cc: Maxime Ripard <mripard@xxxxxxxxxx>
> Cc: Thomas Zimmermann <tzimmermann@xxxxxxx>
> Cc: David Airlie <airlied@xxxxxxxxx>
> Cc: Simona Vetter <simona@xxxxxxxx>
> Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
> Assisted-by: GitHub_Copilot:claude-opus-4.8
> Signed-off-by: Matthew Brost <matthew.brost@xxxxxxxxx>

Reviewed-by: Matthew Auld <matthew.auld@xxxxxxxxx>