linux-kernel - Re: [PATCH] iio: tsl2772: Use device-managed API

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Date:   Sat, 27 Jul 2019 12:57:49 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Chuhong Yuan <hslester96@...il.com>
Cc:     Brian Masney <masneyb@...tation.org>, linux-iio@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: tsl2772: Use device-managed API

On Fri, 26 Jul 2019 20:30:58 +0800
Chuhong Yuan <hslester96@...il.com> wrote:

> Use devm_iio_device_register to simplify
> the code.
> 
> Signed-off-by: Chuhong Yuan <hslester96@...il.com>

Please try to pick up on likely reviewers in your cc list.  In this case
Brian did a lot of work cleaning these drivers up so I've added him.
Not everyone keeps up with the linux-iio list for some reason ;)

Immediate thought was that you had broken the ordering but turns out
it is already buggy.

As things stand, we remove the userspace interfaces (iio_device_unregister)
after turning off the power.   This is obviously a bad idea and also
form a purely "obviously correct" stand point, we aren't doing the reverse
of probe.

So, I 'think' the right option is to reorder remove so that the power left
on until after the iio_device_unregister call. At that point, we can't
use devm_iio_device_register as we'll have the same incorrect ordering
we currently have.

Brian, you looked at this driver most recently.  Thoughts?

Thanks,

Jonathan

> ---
>  drivers/iio/light/tsl2772.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/light/tsl2772.c b/drivers/iio/light/tsl2772.c
> index 83cece921843..aa5891d105e8 100644
> --- a/drivers/iio/light/tsl2772.c
> +++ b/drivers/iio/light/tsl2772.c
> @@ -1877,7 +1877,7 @@ static int tsl2772_probe(struct i2c_client *clientp,
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = iio_device_register(indio_dev);
> +	ret = devm_iio_device_register(&clientp->dev, indio_dev);
>  	if (ret) {
>  		tsl2772_chip_off(indio_dev);
>  		dev_err(&clientp->dev,
> @@ -1928,8 +1928,6 @@ static int tsl2772_remove(struct i2c_client *client)
>  
>  	tsl2772_chip_off(indio_dev);
>  
> -	iio_device_unregister(indio_dev);
> -
>  	return 0;
>  }
>