[Intel-xe] [PATCH] drm/xe: fix mcr semaphore locking for MTL

[Daniele Ceraolo Spurio]

in commit 8604f978f45b ("drm/xe: Convert xe_mmio_wait32 to us so we can
stop using wait_for_us.") the mcr semaphore register read was
accidentally switched from waiting for the register to go to 1 to
waiting for the register to go to 0, so we need to flip it back.

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio at intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Matthew Brost <matthew.brost at intel.com>
---
 drivers/gpu/drm/xe/xe_gt_mcr.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_gt_mcr.c b/drivers/gpu/drm/xe/xe_gt_mcr.c
index c56815af0686..9eb7a6a1348d 100644
--- a/drivers/gpu/drm/xe/xe_gt_mcr.c
+++ b/drivers/gpu/drm/xe/xe_gt_mcr.c
@@ -420,10 +420,11 @@ static void mcr_lock(struct xe_gt *gt)
 	/*
 	 * Starting with MTL we also need to grab a semaphore register
 	 * to synchronize with external agents (e.g., firmware) that now
-	 * shares the same steering control register.
+	 * shares the same steering control register. The semaphore is obtained
+	 * when a read to the relevant register returns 1.
 	 */
 	if (GRAPHICS_VERx100(xe) >= 1270)
-		ret = xe_mmio_wait32(gt, STEER_SEMAPHORE, 0, 0x1, 10, NULL,
+		ret = xe_mmio_wait32(gt, STEER_SEMAPHORE, 0x1, 0x1, 10, NULL,
 				     true);
 
 	drm_WARN_ON_ONCE(&xe->drm, ret == -ETIMEDOUT);
@@ -431,7 +432,7 @@ static void mcr_lock(struct xe_gt *gt)
 
 static void mcr_unlock(struct xe_gt *gt)
 {
-	/* Release hardware semaphore */
+	/* Release hardware semaphore - this is done by writing 1 to the register */
 	if (GRAPHICS_VERx100(gt_to_xe(gt)) >= 1270)
 		xe_mmio_write32(gt, STEER_SEMAPHORE, 0x1);
 
-- 
2.41.0