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Subject[PATCH v2 3/3] drm/v3d: Make sure the GPU is on when measuring clocks.
Date
You'll get garbage measurements if the registers always read back
0xdeadbeef

Signed-off-by: Eric Anholt <eric@anholt.net>
---
drivers/gpu/drm/v3d/v3d_debugfs.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/gpu/drm/v3d/v3d_debugfs.c b/drivers/gpu/drm/v3d/v3d_debugfs.c
index eb2b2d2f8553..a24af2d2f574 100644
--- a/drivers/gpu/drm/v3d/v3d_debugfs.c
+++ b/drivers/gpu/drm/v3d/v3d_debugfs.c
@@ -187,6 +187,11 @@ static int v3d_measure_clock(struct seq_file *m, void *unused)
uint32_t cycles;
int core = 0;
int measure_ms = 1000;
+ int ret;
+
+ ret = pm_runtime_get_sync(v3d->dev);
+ if (ret < 0)
+ return ret;

if (v3d->ver >= 40) {
V3D_CORE_WRITE(core, V3D_V4_PCTR_0_SRC_0_3,
@@ -210,6 +215,9 @@ static int v3d_measure_clock(struct seq_file *m, void *unused)
cycles / (measure_ms * 1000),
(cycles / (measure_ms * 100)) % 10);

+ pm_runtime_mark_last_busy(v3d->dev);
+ pm_runtime_put_autosuspend(v3d->dev);
+
return 0;
}

--
2.20.1
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