On 17.02.2019 17:17, Akinobu Mita wrote:
> 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.
Hi,
This fixes my issue with this sensor in latest mediatree
For anything's worth, for Atmel ISC + ov7740, with my patch,
Tested-by: Eugen Hristev <eugen.hristev@xxxxxxxxxxxxx>
Thanks
>
> 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);
>
>
