[PATCH v2 4/4] drm/xe/guc: READ_ONCE ct state in xe_guc_ct_initialized

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

Use READ_ONCE when reading ct->state in xe_guc_ct_initialized to prevent
the compiler from ignoring this operation.

Fixes: 0b93b7dcd9eb ("drm/xe: Fix early wedge on GuC load failure")
Suggested-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
Cc: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
---
 drivers/gpu/drm/xe/xe_guc_ct.c | 5 ++++-
 drivers/gpu/drm/xe/xe_guc_ct.h | 3 ++-
 2 files changed, 6 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
index c59e38189cf0..24857c2c8cb5 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.c
+++ b/drivers/gpu/drm/xe/xe_guc_ct.c
@@ -530,7 +530,10 @@ static void guc_ct_change_state(struct xe_guc_ct *ct,
 		xe_pm_runtime_put(ct_to_xe(ct));
 	ct->g2h_outstanding = 0;
 
-	/* WRITE_ONCE pairs with READ_ONCE in xe_guc_ct_enabled. */
+	/*
+	 * WRITE_ONCE pairs with READ_ONCEs in xe_guc_ct_initialized and
+	 * xe_guc_ct_enabled.
+	 */
 	WRITE_ONCE(ct->state, state);
 
 	xe_gt_dbg(gt, "GuC CT communication channel %s\n",
diff --git a/drivers/gpu/drm/xe/xe_guc_ct.h b/drivers/gpu/drm/xe/xe_guc_ct.h
index 5f2811a06833..767365a33dee 100644
--- a/drivers/gpu/drm/xe/xe_guc_ct.h
+++ b/drivers/gpu/drm/xe/xe_guc_ct.h
@@ -30,7 +30,8 @@ void xe_guc_ct_print(struct xe_guc_ct *ct, struct drm_printer *p, bool want_ctb)
 
 static inline bool xe_guc_ct_initialized(struct xe_guc_ct *ct)
 {
-	return ct->state != XE_GUC_CT_STATE_NOT_INITIALIZED;
+	/* READ_ONCE pairs with WRITE_ONCE in guc_ct_change_state. */
+	return READ_ONCE(ct->state) != XE_GUC_CT_STATE_NOT_INITIALIZED;
 }
 
 static inline bool xe_guc_ct_enabled(struct xe_guc_ct *ct)
-- 
2.43.0