[PATCH] drm/i915/debug: print time taken to read engine time stamp

[Anshuman Gupta]

print ns taken to read engine timestamps in gt_pm.

Signed-off-by: Anshuman Gupta <anshuman.gupta at intel.com>
---
 drivers/gpu/drm/i915/gt/selftest_gt_pm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/i915/gt/selftest_gt_pm.c b/drivers/gpu/drm/i915/gt/selftest_gt_pm.c
index be94f863bdef..52da0643a00c 100644
--- a/drivers/gpu/drm/i915/gt/selftest_gt_pm.c
+++ b/drivers/gpu/drm/i915/gt/selftest_gt_pm.c
@@ -40,6 +40,7 @@ static void measure_clocks(struct intel_engine_cs *engine,
 			   u32 *out_cycles, ktime_t *out_dt)
 {
 	ktime_t dt[5];
+	ktime_t dt1;
 	u32 cycles[5];
 	int i;
 
@@ -51,7 +52,10 @@ static void measure_clocks(struct intel_engine_cs *engine,
 		udelay(1000);
 
 		dt[i] = ktime_sub(ktime_get(), dt[i]);
+		dt1 = ktime_get();
 		cycles[i] += ENGINE_READ_FW(engine, RING_TIMESTAMP);
+		dt1 = ktime_sub(ktime_get(), dt1);
+		pr_info("%s: time taken to read %lldns\n", engine->name, dt1);
 		local_irq_enable();
 	}
 
-- 
2.38.0