drm/xe: Use spinlock in forcewake instead of mutex

In PMU we need to access certain registers which fall under GT power
domain for which we need to take forcewake. But as PMU being an atomic
context can't expect to have any sleeping calls.
Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Aravind Iddamsetty <aravind.iddamsetty@linux.intel.com>
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_force_wake.c

@@ -42,7 +42,7 @@ void xe_force_wake_init_gt(struct xe_gt *gt, struct xe_force_wake *fw)
 	struct xe_device *xe = gt_to_xe(gt);
 
 	fw->gt = gt;
-	mutex_init(&fw->lock);
+	spin_lock_init(&fw->lock);
 
 	/* Assuming gen11+ so assert this assumption is correct */
 	xe_gt_assert(gt, GRAPHICS_VER(gt_to_xe(gt)) >= 11);
@@ -116,7 +116,7 @@ static int domain_wake_wait(struct xe_gt *gt,
 {
 	return xe_mmio_wait32(gt, domain->reg_ack, domain->val, domain->val,
 			      XE_FORCE_WAKE_ACK_TIMEOUT_MS * USEC_PER_MSEC,
-			      NULL, false);
+			      NULL, true);
 }
 
 static void domain_sleep(struct xe_gt *gt, struct xe_force_wake_domain *domain)
@@ -129,7 +129,7 @@ static int domain_sleep_wait(struct xe_gt *gt,
 {
 	return xe_mmio_wait32(gt, domain->reg_ack, domain->val, 0,
 			      XE_FORCE_WAKE_ACK_TIMEOUT_MS * USEC_PER_MSEC,
-			      NULL, false);
+			      NULL, true);
 }
 
 #define for_each_fw_domain_masked(domain__, mask__, fw__, tmp__) \
@@ -147,7 +147,7 @@ int xe_force_wake_get(struct xe_force_wake *fw,
 	enum xe_force_wake_domains tmp, woken = 0;
 	int ret, ret2 = 0;
 
-	mutex_lock(&fw->lock);
+	spin_lock(&fw->lock);
 	for_each_fw_domain_masked(domain, domains, fw, tmp) {
 		if (!domain->ref++) {
 			woken |= BIT(domain->id);
@@ -162,7 +162,7 @@ int xe_force_wake_get(struct xe_force_wake *fw,
 				   domain->id, ret);
 	}
 	fw->awake_domains |= woken;
-	mutex_unlock(&fw->lock);
+	spin_unlock(&fw->lock);
 
 	return ret2;
 }
@@ -176,7 +176,7 @@ int xe_force_wake_put(struct xe_force_wake *fw,
 	enum xe_force_wake_domains tmp, sleep = 0;
 	int ret, ret2 = 0;
 
-	mutex_lock(&fw->lock);
+	spin_lock(&fw->lock);
 	for_each_fw_domain_masked(domain, domains, fw, tmp) {
 		if (!--domain->ref) {
 			sleep |= BIT(domain->id);
@@ -191,7 +191,7 @@ int xe_force_wake_put(struct xe_force_wake *fw,
 				   domain->id, ret);
 	}
 	fw->awake_domains &= ~sleep;
-	mutex_unlock(&fw->lock);
+	spin_unlock(&fw->lock);
 
 	return ret2;
 }

drivers/gpu/drm/xe/xe_force_wake_types.h

@@ -76,7 +76,7 @@ struct xe_force_wake {
 	/** @gt: back pointers to GT */
 	struct xe_gt *gt;
 	/** @lock: protects everything force wake struct */
-	struct mutex lock;
+	spinlock_t lock;
 	/** @awake_domains: mask of all domains awake */
 	enum xe_force_wake_domains awake_domains;
 	/** @domains: force wake domains */