Re: [PATCH v2 2/6] drm/xe/ggtt: Add xe_ggtt_node_remove_noclear

On Wed, Jul 15, 2026 at 01:05:53PM +0200, Maarten Lankhorst wrote:
> The last bit required for handling fb takeover is
> ensuring we can release the old live framebuffer
> without keeping track. The display code can then
> safely perform the flip.
> 
> It's unfortunately a workaround for how display
> is structured through callbacks instead of being
> a midlayer.
> 
> Signed-off-by: Maarten Lankhorst <[email protected]>

Reviewed-by: Ville Syrjälä <[email protected]>

> ---
>  drivers/gpu/drm/xe/xe_ggtt.c | 30 +++++++++++++++++++++++-------
>  drivers/gpu/drm/xe/xe_ggtt.h |  1 +
>  2 files changed, 24 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_ggtt.c b/drivers/gpu/drm/xe/xe_ggtt.c
> index c9f84db3bfecd..ff479e0a9f3b3 100644
> --- a/drivers/gpu/drm/xe/xe_ggtt.c
> +++ b/drivers/gpu/drm/xe/xe_ggtt.c
> @@ -470,24 +470,40 @@ static void ggtt_node_fini(struct xe_ggtt_node *node)
>  	kfree(node);
>  }
>  
> -static void ggtt_node_remove(struct xe_ggtt_node *node)
> +static void ggtt_node_remove(struct xe_ggtt_node *node, bool clear)
>  {
>  	struct xe_ggtt *ggtt = node->ggtt;
> -	bool bound;
>  
>  	mutex_lock(&ggtt->lock);
> -	bound = ggtt->flags & XE_GGTT_FLAGS_ONLINE;
> -	if (bound)
> +	if (clear)
> +		clear = ggtt->flags & XE_GGTT_FLAGS_ONLINE;
> +	if (clear)
>  		xe_ggtt_clear(ggtt, xe_ggtt_node_addr(node), xe_ggtt_node_size(node));
>  	drm_mm_remove_node(&node->base);
>  	node->base.size = 0;
> -	if (bound && node->invalidate_on_remove)
> +	if (clear && node->invalidate_on_remove)
>  		xe_ggtt_invalidate(ggtt);
>  	mutex_unlock(&ggtt->lock);
>  
>  	ggtt_node_fini(node);
>  }
>  
> +/**
> + * xe_ggtt_node_remove_noclear - Remove a &xe_ggtt_node from the GGTT without clearing entries
> + * @node: the &xe_ggtt_node to be removed
> + *
> + * This function is similar to xe_ggtt_node_remove(), but doesn't clear
> + * the entries. It's used to release the live FB mapping without
> + * clearing it.
> + *
> + * This function should only be called before xe_ggtt_init() in
> + * the bios FB takeover code.
> + */
> +void xe_ggtt_node_remove_noclear(struct xe_ggtt_node *node)
> +{
> +	ggtt_node_remove(node, false);
> +}
> +
>  static void ggtt_node_remove_work_func(struct work_struct *work)
>  {
>  	struct xe_ggtt_node *node = container_of(work, typeof(*node),
> @@ -495,7 +511,7 @@ static void ggtt_node_remove_work_func(struct work_struct *work)
>  	struct xe_device *xe = tile_to_xe(node->ggtt->tile);
>  
>  	guard(xe_pm_runtime)(xe);
> -	ggtt_node_remove(node);
> +	ggtt_node_remove(node, true);
>  }
>  
>  /**
> @@ -517,7 +533,7 @@ void xe_ggtt_node_remove(struct xe_ggtt_node *node, bool invalidate)
>  	node->invalidate_on_remove = invalidate;
>  
>  	if (xe_pm_runtime_get_if_active(xe)) {
> -		ggtt_node_remove(node);
> +		ggtt_node_remove(node, true);
>  		xe_pm_runtime_put(xe);
>  	} else {
>  		queue_work(ggtt->wq, &node->delayed_removal_work);
> diff --git a/drivers/gpu/drm/xe/xe_ggtt.h b/drivers/gpu/drm/xe/xe_ggtt.h
> index 69974da523f74..83654544feb6d 100644
> --- a/drivers/gpu/drm/xe/xe_ggtt.h
> +++ b/drivers/gpu/drm/xe/xe_ggtt.h
> @@ -32,6 +32,7 @@ xe_ggtt_insert_node_transform(struct xe_ggtt *ggtt,
>  			      u64 size, u32 align,
>  			      xe_ggtt_transform_cb transform, void *arg);
>  void xe_ggtt_node_remove(struct xe_ggtt_node *node, bool invalidate);
> +void xe_ggtt_node_remove_noclear(struct xe_ggtt_node *node);
>  size_t xe_ggtt_node_pt_size(const struct xe_ggtt_node *node);
>  void xe_ggtt_map_bo_unlocked(struct xe_ggtt *ggtt, struct xe_bo *bo);
>  int xe_ggtt_insert_bo(struct xe_ggtt *ggtt, struct xe_bo *bo, struct drm_exec *exec);
> -- 
> 2.53.0

-- 
Ville Syrjälä
Intel