drm/xe/xe2: Make subsequent L2 flush sequential

Issuing the flush on top of an ongoing flush is not desirable.
Lets use lock to make it sequential.
Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>
Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240710052750.3031586-1-tejas.upadhyay@intel.comSigned-off-by: Nirmoy Das <nirmoy.das@intel.com>

drivers/gpu/drm/xe/xe_device.c

@@ -833,10 +833,12 @@ void xe_device_l2_flush(struct xe_device *xe)
 	if (err)
 		return;
 
+	spin_lock(&gt->global_invl_lock);
 	xe_mmio_write32(gt, XE2_GLOBAL_INVAL, 0x1);
 
 	if (xe_mmio_wait32(gt, XE2_GLOBAL_INVAL, 0x1, 0x0, 150, NULL, true))
 		xe_gt_err_once(gt, "Global invalidation timeout\n");
+	spin_unlock(&gt->global_invl_lock);
 
 	xe_force_wake_put(gt_to_fw(gt), XE_FW_GT);
 }

drivers/gpu/drm/xe/xe_gt.c

@@ -387,6 +387,7 @@ int xe_gt_init_early(struct xe_gt *gt)
 
 	xe_force_wake_init_gt(gt, gt_to_fw(gt));
 	xe_pcode_init(gt);
+	spin_lock_init(&gt->global_invl_lock);
 
 	return 0;
 }

drivers/gpu/drm/xe/xe_gt_types.h

@@ -362,6 +362,12 @@ struct xe_gt {
 	 */
 	spinlock_t mcr_lock;
 
+	/**
+	 * @global_invl_lock: protects the register for the duration
+	 *    of a global invalidation of l2 cache
+	 */
+	spinlock_t global_invl_lock;
+
 	/** @wa_active: keep track of active workarounds */
 	struct {
 		/** @wa_active.gt: bitmap with active GT workarounds */