[PATCH v2 3/3] media: i2c: ov5693: Use autosuspend when stopping the stream

[Marco Ziliani]

The driver enables runtime PM autosuspend with a 1 second delay at
probe, but drops the usage count at stream stop with pm_runtime_put(),
which doesn't update the device's last busy time. The autosuspend
delay is then counted from the runtime resume at stream start rather
than from stream stop, so after any stream longer than the delay the
sensor is powered off right away.

Use pm_runtime_put_autosuspend(), which marks the device busy, so that
the delay counts from stream stop as intended, and a following stream
started within it doesn't power the sensor up from scratch again. With
the mode now programmed on every stream start, keeping the sensor
powered between streams no longer leaves it in a stale mode.

On a Surface Pro 9 (IPU6) with autosuspend_delay_ms set to 3000, the
sensor suspended 1-2 ms after a 5 s stream stopped; with this change,
3.7 s after it, i.e. the delay plus the autosuspend timer slack. On a
Surface Pro 5 (IPU3) with the default 1 s delay, the sensor suspended
as soon as a 2 s stream stopped; with this change, 1.1 s after it.

Fixes: 89aef879cb53 ("media: i2c: Add support for ov5693 sensor")
Reported-by: D. Manresa <dmanresa@xxxxxxxxx>
Closes: https://github.com/linux-surface/kernel/pull/181#issuecomment-6436016335
Reviewed-by: Daniel Scally <dan.scally@xxxxxxxxxxxxxxxx>
Tested-by: Chris Simpson <chris@xxxxxxxx>
Tested-by: Tony Garcia <tony@xxxxxxxxxxxx>
Signed-off-by: Marco Ziliani <rylos78@xxxxxxxxx>
---
 drivers/media/i2c/ov5693.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/media/i2c/ov5693.c b/drivers/media/i2c/ov5693.c
index 9fedc087e..086f9df07 100644
--- a/drivers/media/i2c/ov5693.c
+++ b/drivers/media/i2c/ov5693.c
@@ -1065,7 +1065,7 @@ static int ov5693_s_stream(struct v4l2_subdev *sd, int enable)
 		goto err_power_down;
 
 	if (!enable)
-		pm_runtime_put(ov5693->dev);
+		pm_runtime_put_autosuspend(ov5693->dev);
 
 	return 0;
 err_power_down:

-- 
2.56.0