[PATCH v10 2/4] drm/xe: Add locks in gtidle code

[Vinay Belgaumkar]

Another entry point is added so PMU code can call into the gtidle
method for residency. Add locking so that parallel calls to this
method from sysfs and PMU don't give inconsistent gtidle states
for c6 residency.

Suggested-by: Lucas De Marchi <lucas.demarchi at intel.com>
Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
Cc: Lucas De Marchi <lucas.demarchi at intel.com>
Signed-off-by: Vinay Belgaumkar <vinay.belgaumkar at intel.com>
---
 drivers/gpu/drm/xe/xe_gt_idle.c       | 23 ++++++++++++++++++++---
 drivers/gpu/drm/xe/xe_gt_idle.h       |  1 +
 drivers/gpu/drm/xe/xe_gt_idle_types.h |  3 +++
 3 files changed, 24 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_gt_idle.c b/drivers/gpu/drm/xe/xe_gt_idle.c
index fd80afeef56a..1f32ac964abe 100644
--- a/drivers/gpu/drm/xe/xe_gt_idle.c
+++ b/drivers/gpu/drm/xe/xe_gt_idle.c
@@ -69,6 +69,8 @@ static u64 get_residency_ms(struct xe_gt_idle *gtidle, u64 cur_residency)
 {
 	u64 delta, overflow_residency, prev_residency;
 
+	lockdep_assert_held(&gtidle->lock);
+
 	overflow_residency = BIT_ULL(32);
 
 	/*
@@ -273,8 +275,21 @@ static ssize_t idle_status_show(struct device *dev,
 
 	return sysfs_emit(buff, "%s\n", gt_idle_state_to_string(state));
 }
-static DEVICE_ATTR_RO(idle_status);
 
+u64 xe_gt_idle_residency_msec(struct xe_gt_idle *gtidle)
+{
+	struct xe_guc_pc *pc = gtidle_to_pc(gtidle);
+	u64 residency;
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&gtidle->lock, flags);
+	residency = get_residency_ms(gtidle, gtidle->idle_residency(pc));
+	raw_spin_unlock_irqrestore(&gtidle->lock, flags);
+
+	return residency;
+}
+
+static DEVICE_ATTR_RO(idle_status);
 static ssize_t idle_residency_ms_show(struct device *dev,
 				      struct device_attribute *attr, char *buff)
 {
@@ -283,10 +298,10 @@ static ssize_t idle_residency_ms_show(struct device *dev,
 	u64 residency;
 
 	xe_pm_runtime_get(pc_to_xe(pc));
-	residency = gtidle->idle_residency(pc);
+	residency = xe_gt_idle_residency_msec(gtidle);
 	xe_pm_runtime_put(pc_to_xe(pc));
 
-	return sysfs_emit(buff, "%llu\n", get_residency_ms(gtidle, residency));
+	return sysfs_emit(buff, "%llu\n", residency);
 }
 static DEVICE_ATTR_RO(idle_residency_ms);
 
@@ -329,6 +344,8 @@ int xe_gt_idle_init(struct xe_gt_idle *gtidle)
 	if (!kobj)
 		return -ENOMEM;
 
+	raw_spin_lock_init(&gtidle->lock);
+
 	if (xe_gt_is_media_type(gt)) {
 		snprintf(gtidle->name, sizeof(gtidle->name), "gt%d-mc", gt->info.id);
 		gtidle->idle_residency = xe_guc_pc_mc6_residency;
diff --git a/drivers/gpu/drm/xe/xe_gt_idle.h b/drivers/gpu/drm/xe/xe_gt_idle.h
index 4455a6501cb0..591a01e181bc 100644
--- a/drivers/gpu/drm/xe/xe_gt_idle.h
+++ b/drivers/gpu/drm/xe/xe_gt_idle.h
@@ -17,5 +17,6 @@ void xe_gt_idle_disable_c6(struct xe_gt *gt);
 void xe_gt_idle_enable_pg(struct xe_gt *gt);
 void xe_gt_idle_disable_pg(struct xe_gt *gt);
 int xe_gt_idle_pg_print(struct xe_gt *gt, struct drm_printer *p);
+u64 xe_gt_idle_residency_msec(struct xe_gt_idle *gtidle);
 
 #endif /* _XE_GT_IDLE_H_ */
diff --git a/drivers/gpu/drm/xe/xe_gt_idle_types.h b/drivers/gpu/drm/xe/xe_gt_idle_types.h
index b8b297a3f884..a3667c567f8a 100644
--- a/drivers/gpu/drm/xe/xe_gt_idle_types.h
+++ b/drivers/gpu/drm/xe/xe_gt_idle_types.h
@@ -6,6 +6,7 @@
 #ifndef _XE_GT_IDLE_SYSFS_TYPES_H_
 #define _XE_GT_IDLE_SYSFS_TYPES_H_
 
+#include <linux/spinlock.h>
 #include <linux/types.h>
 
 struct xe_guc_pc;
@@ -31,6 +32,8 @@ struct xe_gt_idle {
 	u64 cur_residency;
 	/** @prev_residency: previous residency counter */
 	u64 prev_residency;
+	/** @lock: Lock protecting idle residency counters */
+	raw_spinlock_t lock;
 	/** @idle_status: get the current idle state */
 	enum xe_gt_idle_state (*idle_status)(struct xe_guc_pc *pc);
 	/** @idle_residency: get idle residency counter */
-- 
2.38.1