drm/ttm: improve idle/busy handling v5

Previously we would never try to move a BO into the preferred placements
when it ever landed in a busy placement since those were considered
compatible.

Rework the whole handling and finally unify the idle and busy handling.
ttm_bo_validate() is now responsible to try idle placement first and then
use the busy placement if that didn't worked.

Drawback is that we now always try the idle placement first for each
validation which might cause some additional CPU overhead on overcommit.

v2: fix kerneldoc warning and coding style
v3: take care of XE as well
v4: keep the ttm_bo_mem_space functionality as it is for now, only add
    new handling for ttm_bo_validate as suggested by Thomas
v5: fix bug pointed out by Matthew

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Zack Rusin <zack.rusin@broadcom.com> v3
Link: https://patchwork.freedesktop.org/patch/msgid/20240229134003.3688-1-christian.koenig@amd.com
Reviewed-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

1 files changed, 12 insertions, 4 deletions

diff --git a/drivers/gpu/drm/ttm/ttm_resource.c b/drivers/gpu/drm/ttm/ttm_resource.c
index fb14f7716cf8..65155f2013ca 100644
--- a/drivers/gpu/drm/ttm/ttm_resource.c
+++ b/drivers/gpu/drm/ttm/ttm_resource.c
@@ -295,11 +295,13 @@ bool ttm_resource_intersects(struct ttm_device *bdev,
  *
  * @res: the resource to check
  * @placement: the placement to check against
+ * @evicting: true if the caller is doing evictions
  *
  * Returns true if the placement is compatible.
  */
 bool ttm_resource_compatible(struct ttm_resource *res,
-			     struct ttm_placement *placement)
+			     struct ttm_placement *placement,
+			     bool evicting)
 {
 	struct ttm_buffer_object *bo = res->bo;
 	struct ttm_device *bdev = bo->bdev;
@@ -315,14 +317,20 @@ bool ttm_resource_compatible(struct ttm_resource *res,
 		if (res->mem_type != place->mem_type)
 			continue;
 
+		if (place->flags & (evicting ? TTM_PL_FLAG_DESIRED :
+				    TTM_PL_FLAG_FALLBACK))
+			continue;
+
+		if (place->flags & TTM_PL_FLAG_CONTIGUOUS &&
+		    !(res->placement & TTM_PL_FLAG_CONTIGUOUS))
+			continue;
+
 		man = ttm_manager_type(bdev, res->mem_type);
 		if (man->func->compatible &&
 		    !man->func->compatible(man, res, place, bo->base.size))
 			continue;
 
-		if ((!(place->flags & TTM_PL_FLAG_CONTIGUOUS) ||
-		     (res->placement & TTM_PL_FLAG_CONTIGUOUS)))
-			return true;
+		return true;
 	}
 	return false;
 }