[Intel-xe] [RFC PATCH 2/3] drm/xe : add rc6_residency in ms

[Riana Tauro]

add rc6_residency in ms instead of rc6 residency counter.
Handle wrap around for the counter
The counter can still wrap as it relies on the frequency of
counter being read

Signed-off-by: Riana Tauro <riana.tauro at intel.com>
---
 drivers/gpu/drm/xe/xe_idle.c | 46 +++++++++++++++++++++++++++++-------
 1 file changed, 37 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_idle.c b/drivers/gpu/drm/xe/xe_idle.c
index 231bdb45a6b7..a7e97ddd7253 100644
--- a/drivers/gpu/drm/xe/xe_idle.c
+++ b/drivers/gpu/drm/xe/xe_idle.c
@@ -11,6 +11,8 @@
 #include "xe_idle.h"
 #include "xe_mmio.h"
 
+#define XE_RC6_MULTIPLIER      1280
+
 /*
  * Render-C States:
  * ================
@@ -27,8 +29,7 @@
  *
  * device/gt#/gpu_idle/rc* *read-only* files:
  * - rc_status: Provide the actual immediate status of Render-C: (rc0 or rc6)
- * - rc6_residency: Provide the rc6_residency in units of 1.28 uSec
- *		    Prone to overflows.
+ * - rc6_residency_ms: Provide the rc6_residency in ms
  */
 
 static struct xe_gt *idle_to_gt(struct xe_idle *idle)
@@ -51,6 +52,35 @@ static struct kobj_type xe_idle_kobj_type = {
 	.sysfs_ops = &kobj_sysfs_ops,
 };
 
+static u64 rc6_residency_us(struct xe_idle *idle)
+{
+	struct xe_gt *gt = idle_to_gt(idle);
+	u64 cur_residency, delta, overflow_residency, prev_residency;
+
+	overflow_residency = BIT_ULL(32);
+	cur_residency = xe_mmio_read32(gt, GEN6_GT_GFX_RC6.reg);
+
+	/*
+	 * Counter wrap handling
+	 * Store previous hw counter values for counter wrap-around handling
+	 * Relying on sufficient frequency of queries otherwise counters can still wrap.
+	 */
+	prev_residency = idle->prev_rc6_residency;
+	idle->prev_rc6_residency = cur_residency;
+
+	/* RC6 delta */
+	if (cur_residency >= prev_residency)
+		delta = cur_residency - prev_residency;
+	else
+		delta = cur_residency + (overflow_residency - prev_residency);
+
+	/* Add delta to RC6 extended raw driver copy. */
+	cur_residency = idle->cur_rc6_residency + delta;
+	idle->cur_rc6_residency = cur_residency;
+
+	return mul_u64_u32_div(cur_residency, XE_RC6_MULTIPLIER, 1000);
+}
+
 static ssize_t
 rc_status_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 {
@@ -76,11 +106,10 @@ static const struct kobj_attribute rc_status =
 __ATTR(rc_status, 0444, rc_status_show, NULL);
 
 static ssize_t
-rc6_residency_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
+rc6_residency_ms_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 {
 	struct xe_idle *idle = kobj_to_idle(kobj);
 	struct xe_gt *gt = idle_to_gt(idle);
-	u32 reg;
 	ssize_t ret;
 
 	xe_device_mem_access_get(gt_to_xe(gt));
@@ -88,8 +117,7 @@ rc6_residency_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 	if (ret)
 		goto out;
 
-	reg = xe_mmio_read32(gt, GEN6_GT_GFX_RC6.reg);
-	ret = sysfs_emit(buf, "%u\n", reg);
+	ret = sysfs_emit(buf, "%llu\n", DIV_ROUND_UP_ULL(rc6_residency_us(&gt->idle), 1000));
 
 	XE_WARN_ON(xe_force_wake_put(gt_to_fw(gt), XE_FORCEWAKE_ALL));
 out:
@@ -97,12 +125,12 @@ rc6_residency_show(struct kobject *kobj, struct kobj_attribute *attr, char *buf)
 	return ret;
 }
 
-static const struct kobj_attribute rc6_residency =
-__ATTR(rc6_residency, 0444, rc6_residency_show, NULL);
+static const struct kobj_attribute rc6_residency_ms =
+__ATTR(rc6_residency_ms, 0444, rc6_residency_ms_show, NULL);
 
 static const struct attribute *idle_attrs[] = {
 	&rc_status.attr,
-	&rc6_residency.attr,
+	&rc6_residency_ms.attr,
 	NULL,
 };
 
-- 
2.40.0