drm/xe: Allow GT looping and lookup on standalone media

Allow xe_device_get_gt() and for_each_gt() to operate as expected on
platforms with standalone media.

FIXME: We need to figure out a consistent ID scheme for GTs.  This patch
keeps the pre-existing behavior of 0/1 being the GT IDs for both PVC
(multi-tile) and MTL (multi-GT), but depending on the direction we
decide to go with uapi, we may change this in the future (e.g., to
return 0/1 on PVC and 0/2 on MTL).  Or if we decide we only need to
expose tiles to userspace and not GTs, we may not even need ID numbers
for the GTs anymore.

v2:
 - Restructure a bit to make the assertions more clear.
 - Clarify in commit message that the goal here is to preserve existing
   behavior; UAPI-visible changes may be introduced in the future once
   we settle on what we really want.
v3:
 - Store total GT count in xe_device for ease of lookup.  (Brian)
 - s/(id__++)/(id__)++/  (Gustavo)

Cc: Lucas De Marchi <lucas.demarchi@intel.com>
Cc: Gustavo Sousa <gustavo.sousa@intel.com>
Cc: Brian Welty <brian.welty@intel.com>
Acked-by: Gustavo Sousa <gustavo.sousa@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20230601215244.678611-29-matthew.d.roper@intel.comSigned-off-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_device.h

@@ -53,18 +53,42 @@ static inline struct xe_tile *xe_device_get_root_tile(struct xe_device *xe)
 	return &xe->tiles[0];
 }
 
+#define XE_MAX_GT_PER_TILE 2
+
+static inline struct xe_gt *xe_tile_get_gt(struct xe_tile *tile, u8 gt_id)
+{
+	if (drm_WARN_ON(&tile_to_xe(tile)->drm, gt_id > XE_MAX_GT_PER_TILE))
+		gt_id = 0;
+
+	return gt_id ? tile->media_gt : tile->primary_gt;
+}
+
 static inline struct xe_gt *xe_device_get_gt(struct xe_device *xe, u8 gt_id)
 {
+	struct xe_tile *root_tile = xe_device_get_root_tile(xe);
 	struct xe_gt *gt;
 
-	XE_BUG_ON(gt_id > XE_MAX_TILES_PER_DEVICE);
-
-	gt = xe->tiles[gt_id].primary_gt;
-	if (drm_WARN_ON(&xe->drm, !gt))
+	/*
+	 * FIXME: This only works for now because multi-tile and standalone
+	 * media are mutually exclusive on the platforms we have today.
+	 *
+	 * id => GT mapping may change once we settle on how we want to handle
+	 * our UAPI.
+	 */
+	if (MEDIA_VER(xe) >= 13) {
+		gt = xe_tile_get_gt(root_tile, gt_id);
+	} else {
+		if (drm_WARN_ON(&xe->drm, gt_id > XE_MAX_TILES_PER_DEVICE))
+			gt_id = 0;
+
+		gt = xe->tiles[gt_id].primary_gt;
+	}
+
+	if (!gt)
 		return NULL;
 
-	XE_BUG_ON(gt->info.id != gt_id);
-	XE_BUG_ON(gt->info.type == XE_GT_TYPE_UNINITIALIZED);
+	drm_WARN_ON(&xe->drm, gt->info.id != gt_id);
+	drm_WARN_ON(&xe->drm, gt->info.type == XE_GT_TYPE_UNINITIALIZED);
 
 	return gt;
 }
@@ -100,8 +124,12 @@ static inline void xe_device_guc_submission_disable(struct xe_device *xe)
 	for ((id__) = 0; (id__) < (xe__)->info.tile_count; (id__)++) \
 		for_each_if ((tile__) = &(xe__)->tiles[(id__)])
 
+/*
+ * FIXME: This only works for now since multi-tile and standalone media
+ * happen to be mutually exclusive.  Future platforms may change this...
+ */
 #define for_each_gt(gt__, xe__, id__) \
-	for ((id__) = 0; (id__) < (xe__)->info.tile_count; (id__++)) \
+	for ((id__) = 0; (id__) < (xe__)->info.gt_count; (id__)++) \
 		for_each_if ((gt__) = xe_device_get_gt((xe__), (id__)))
 
 static inline struct xe_force_wake * gt_to_fw(struct xe_gt *gt)

drivers/gpu/drm/xe/xe_device_types.h

@@ -184,6 +184,8 @@ struct xe_device {
 		u8 vram_flags;
 		/** @tile_count: Number of tiles */
 		u8 tile_count;
+		/** @gt_count: Total number of GTs for entire device */
+		u8 gt_count;
 		/** @vm_max_level: Max VM level */
 		u8 vm_max_level;
 

drivers/gpu/drm/xe/xe_pci.c

@@ -535,7 +535,11 @@ static int xe_info_init(struct xe_device *xe,
 			return PTR_ERR(tile->primary_gt);
 
 		gt = tile->primary_gt;
-		gt->info.id = id;	/* FIXME: Determine sensible numbering */
+		/*
+		 * FIXME: GT numbering scheme may change depending on UAPI
+		 * decisions.
+		 */
+		gt->info.id = xe->info.gt_count++;
 		gt->info.type = XE_GT_TYPE_MAIN;
 		gt->info.__engine_mask = graphics_desc->hw_engine_mask;
 		if (MEDIA_VER(xe) < 13 && media_desc)