The runtime PM of this device is enabled after v4l2_ctrl_handler_setup(),
and this makes this device's runtime PM usage count a negative value.
The ov7740_set_ctrl() tries to do something only if the device's runtime
PM usage counter is nonzero.
ov7740_set_ctrl()
{
if (!pm_runtime_get_if_in_use(&client->dev))
return 0;
<do something>;
pm_runtime_put(&client->dev);
return ret;
}
However, the ov7740_set_ctrl() is called by v4l2_ctrl_handler_setup()
while the runtime PM of this device is not yet enabled. In this case,
the pm_runtime_get_if_in_use() returns -EINVAL (!= 0).
Therefore we can't bail out of this function and the usage count is
decreased by pm_runtime_put() without increment.
This fixes this problem by enabling the runtime PM of this device before
v4l2_ctrl_handler_setup() so that the ov7740_set_ctrl() is always called
when the runtime PM is enabled.
Cc: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx>
Cc: Wenyou Yang <wenyou.yang@xxxxxxxxxxxxx>
Cc: Sakari Ailus <sakari.ailus@xxxxxxxxxxxxxxx>
Cc: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
Signed-off-by: Akinobu Mita <akinobu.mita@xxxxxxxxx>
---
I don't have the ov7740 device, but I saw the same problem with the
mt9m001 device when I was adding the runtime PM support for it.
Eugen Hristev reported the problem with ov7740.
https://www.mail-archive.com/linux-media@xxxxxxxxxxxxxxx/msg144540.html
I suspect that it is related to this runtime PM problem.
There seems to be the same problem in other devices. I would like to see
if this patch actually fix the ov7740's problem and then propagate other
devices.
drivers/media/i2c/ov7740.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/drivers/media/i2c/ov7740.c b/drivers/media/i2c/ov7740.c
index 177688a..8835b83 100644
--- a/drivers/media/i2c/ov7740.c
+++ b/drivers/media/i2c/ov7740.c
@@ -1101,6 +1101,9 @@ static int ov7740_probe(struct i2c_client *client,
if (ret)
return ret;
+ pm_runtime_set_active(&client->dev);
+ pm_runtime_enable(&client->dev);
+
ret = ov7740_detect(ov7740);
if (ret)
goto error_detect;
@@ -1123,8 +1126,6 @@ static int ov7740_probe(struct i2c_client *client,
if (ret)
goto error_async_register;
- pm_runtime_set_active(&client->dev);
- pm_runtime_enable(&client->dev);
pm_runtime_idle(&client->dev);
return 0;
@@ -1134,6 +1135,8 @@ static int ov7740_probe(struct i2c_client *client,
error_init_controls:
ov7740_free_controls(ov7740);
error_detect:
+ pm_runtime_disable(&client->dev);
+ pm_runtime_set_suspended(&client->dev);
ov7740_set_power(ov7740, 0);
media_entity_cleanup(&ov7740->subdev.entity);
--
2.7.4
