[PATCH 11/11] drm/xe: Allow probe without a primary GT

[Stuart Summers <stuart.summers@intel.com>]

Probe required a graphics IP and a primary GT, so the media only
combination the gt_types_allowed configfs attribute can ask for was
rejected outright.

Require instead that something is left to drive: at least one of the two
IPs has to be detected, and every tile has to end up with at least one
GT. The dgpu concern the old comment raised is covered by VRAM being a
graphics IP property, so a device without one has no VRAM to manage.

Signed-off-by: Stuart Summers <stuart.summers@intel.com>
---
 drivers/gpu/drm/xe/xe_pci.c | 25 +++++++++----------------
 1 file changed, 9 insertions(+), 16 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
index 05aea5498a7b..e67b00557c0d 100644
--- a/drivers/gpu/drm/xe/xe_pci.c
+++ b/drivers/gpu/drm/xe/xe_pci.c
@@ -1029,11 +1029,11 @@ static int xe_probe_ips(struct xe_device *xe,
 	}
 
 	/*
-	 * If we couldn't detect the graphics IP, that's considered a fatal
-	 * error and we should abort driver load.  Failing to detect media
-	 * IP is non-fatal; we'll just proceed without enabling media support.
+	 * Either IP on its own is enough to go on with.  Only a device where
+	 * neither could be detected is a fatal error, since there would be
+	 * nothing left to drive.
 	 */
-	if (!probed_info->graphics_ip)
+	if (!probed_info->graphics_ip && !probed_info->media_ip)
 		return -ENODEV;
 
 	return 0;
@@ -1148,21 +1148,14 @@ static int xe_info_init(struct xe_device *xe,
 		if (IS_ERR(tile->primary_gt))
 			return PTR_ERR(tile->primary_gt);
 
-		/*
-		 * It's not currently possible to probe a device with the
-		 * primary GT disabled.  With some work, this may be future in
-		 * the possible for igpu platforms (although probably not for
-		 * dgpu's since access to the primary GT's BCS engines is
-		 * required for VRAM management).
-		 */
-		if (!tile->primary_gt) {
-			drm_err(&xe->drm, "Cannot probe device with without a primary GT\n");
-			return -ENODEV;
-		}
-
 		tile->media_gt = alloc_media_gt(tile, media_desc);
 		if (IS_ERR(tile->media_gt))
 			return PTR_ERR(tile->media_gt);
+
+		if (!tile->primary_gt && !tile->media_gt) {
+			xe_tile_err(tile, "Cannot probe tile without any GT\n");
+			return -ENODEV;
+		}
 	}
 
 	/*
-- 
2.43.0