drm/xe: fix mcr semaphore locking for MTL

in commit 81593af6c88d ("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@intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

diff --git a/drivers/gpu/drm/xe/xe_gt_mcr.c b/drivers/gpu/drm/xe/xe_gt_mcr.c
index c56815a..9eb7a6a 100644 (file)
--- 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);