[PATCH] drm/xe/xe_guc: Expand guc_g2g_alloc error hanlding for future change

[Jonathan Cavitt <jonathan.cavitt@intel.com>]

On today's driver, xe_device_get_gt(xe, 0); can never return NULL.
Hardware-wise there's always at least one tile, and every tilie has a
primary GT.  If something went wrong during init of tile or GT and we
couldn't create/initialize the structures, then we already aborted the
device probe immediately and we'll never get further on to places in the
code that would be chasing a NULL pointer.

However, there's currently ongoing work to allow the primary GT to be
disabled via configfs for debugging purposes.  Once that lands, it will
be possible for this query to return a NULL pointer.  Expand the error
handling code for guc_g2g_alloc to manage this in the future.

Suggested-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Suggested-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
---
 drivers/gpu/drm/xe/xe_guc.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/xe/xe_guc.c b/drivers/gpu/drm/xe/xe_guc.c
index d94490979adc..fbe66722e852 100644
--- a/drivers/gpu/drm/xe/xe_guc.c
+++ b/drivers/gpu/drm/xe/xe_guc.c
@@ -467,9 +467,13 @@ static int guc_g2g_alloc(struct xe_guc *guc)
 
 	if (gt->info.id != 0) {
 		struct xe_gt *root_gt = xe_device_get_gt(xe, 0);
-		struct xe_guc *root_guc = &root_gt->uc.guc;
+		struct xe_guc *root_guc;
 		struct xe_bo *bo;
 
+		if (!root_gt)
+			return -ENODEV;
+
+		root_guc = &root_gt->uc.guc;
 		bo = xe_bo_get(root_guc->g2g.bo);
 		if (!bo)
 			return -ENODEV;
-- 
2.43.0