drm/xe: Clarify GT counting logic

The total number of GTs supported by a platform should be one primary
GT, one media GT (if media version >= 13), and a number of remote tile
GTs dependent on the graphics IP present.  Express this more clearly in
the device setup.

Note that xe->info.tile_count is inaccurately named; the rest of the
driver treats this as the GT count, not just the tile count.  This
will need to be cleaned up at some point down the road.
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://lore.kernel.org/r/20230406235621.1914492-6-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_pci.c

@@ -124,7 +124,7 @@ static const struct xe_graphics_desc graphics_xehpc = {
 
 	XE_HP_FEATURES,
 	.dma_mask_size = 52,
-	.max_tiles = 2,
+	.max_remote_tiles = 1,
 	.vm_max_level = 4,
 	.vram_flags = XE_VRAM_FLAGS_NEED64K,
 
@@ -143,8 +143,6 @@ static const struct xe_graphics_desc graphics_xelpg = {
 		BIT(XE_HW_ENGINE_CCS0),
 
 	XE_HP_FEATURES,
-	.max_tiles = 2,
-
 	.has_flat_ccs = 0,
 };
 
@@ -388,7 +386,6 @@ static void xe_info_init(struct xe_device *xe,
 	xe->info.platform = desc->platform;
 	xe->info.dma_mask_size = desc->graphics->dma_mask_size;
 	xe->info.vram_flags = desc->graphics->vram_flags;
-	xe->info.tile_count = desc->graphics->max_tiles ?: 1;
 	xe->info.vm_max_level = desc->graphics->vm_max_level;
 	xe->info.supports_usm = desc->graphics->supports_usm;
 	xe->info.has_asid = desc->graphics->has_asid;
@@ -397,6 +394,19 @@ static void xe_info_init(struct xe_device *xe,
 	xe->info.has_range_tlb_invalidation = desc->graphics->has_range_tlb_invalidation;
 	xe->info.has_link_copy_engine = desc->graphics->has_link_copy_engine;
 
+	/*
+	 * All platforms have at least one primary GT.  Any platform with media
+	 * version 13 or higher has an additional dedicated media GT.  And
+	 * depending on the graphics IP there may be additional "remote tiles."
+	 * All of these together determine the overall GT count.
+	 *
+	 * FIXME: 'tile_count' here is misnamed since the rest of the driver
+	 * treats it as the number of GTs rather than just the number of tiles.
+	 */
+	xe->info.tile_count = 1 + desc->graphics->max_remote_tiles;
+	if (MEDIA_VER(xe) >= 13)
+		xe->info.tile_count++;
+
 	xe->info.subplatform = subplatform_desc ?
 		subplatform_desc->subplatform : XE_SUBPLATFORM_NONE;
 	xe->info.step = xe_step_get(xe);

drivers/gpu/drm/xe/xe_pci_types.h

@@ -13,12 +13,13 @@ struct xe_graphics_desc {
 	u8 rel;
 
 	u8 dma_mask_size;	/* available DMA address bits */
-	u8 max_tiles;		/* defaults to 1 if unset */
 	u8 vm_max_level;
 	u8 vram_flags;
 
 	u64 hw_engine_mask;	/* hardware engines provided by graphics IP */
 
+	u8 max_remote_tiles:2;
+
 	u8 has_asid:1;
 	u8 has_flat_ccs:1;
 	u8 has_link_copy_engine:1;