linux-kernel - Re: [PATCH v2] iio: light: tsl2583: Fix module unloading

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Message-ID: <2bbbd71a-904f-2bdf-8dda-f699e38265f8@collabora.com>
Date:   Wed, 31 Aug 2022 19:20:38 +0530
From:   Shreeya Patel <shreeya.patel@...labora.com>
To:     Jonathan Cameron <jic23@...nel.org>
Cc:     lars@...afoo.de, krisman@...labora.com,
        dmitry.osipenko@...labora.com, kernel@...labora.com,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH v2] iio: light: tsl2583: Fix module unloading


On 28/08/22 22:03, Jonathan Cameron wrote:
> On Fri, 26 Aug 2022 17:53:52 +0530
> Shreeya Patel <shreeya.patel@...labora.com> wrote:
>
>> tsl2583 uses devm_iio_device_register() function and
>> calling iio_device_unregister() in remove breaks the
>> module unloading.
>> Fix this by using iio_device_register() instead of
>> devm_iio_device_register() function in probe.
> Not sure why you are wrapping at 55 chars. I rewrapped this whilst applying.
>
> Reworded it a little too as I was touching it anyway.
>
> Applied to the fixes-togreg branch of iio.git.
>
>> Cc: stable@...r.kernel.org
>> Fixes: 371894f5d1a0 ("iio: tsl2583: add runtime power management support")
> I took a look at this patch and it introduces the issue I just pointed
> out in replying to your v1 by dropping the
> /* Make sure the chip is on */
> Which was correct even with runtime pm because it covered the case of
> runtime_pm being disabled.   We probably need to bring that back as well,
> perhaps as part of a cleanup patch taking this fully devm_

Hi Jonathan,

I can work on fixing some of the issues with this driver in my free time.
Thanks for taking a look at the patch and letting me know.

FYI, I am also planning to work on ADT7316 driver to move out of staging.
I have the adt7516 eval board with me which I'll be using for testing.


Thanks,
Shreeya Patel

> This driver has another issue for working if runtime PM isn't built into
> the kernel which is that it checks the return of pm_runtime_put_autosuspend()
> which calls
>
> static inline int __pm_runtime_suspend(struct device *dev, int rpmflags)
> {
> 	return -ENOSYS;
> }
>
> I've been meaning to do an audit for drivers that have this problem for
> a while, but not yet gotten to it.
>
> An ideal IIO driver needs to work correctly whether or not CONFIG_PM is
> enabled.
>
> Jonathan
>
>
>> Signed-off-by: Shreeya Patel <shreeya.patel@...labora.com>
>> ---
>> Changes in v2
>>    - Use iio_device_register() instead of devm_iio_device_register()
>>    - Add fixes and stable tags
>>
>>   drivers/iio/light/tsl2583.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/iio/light/tsl2583.c b/drivers/iio/light/tsl2583.c
>> index 82662dab87c0..94d75ec687c3 100644
>> --- a/drivers/iio/light/tsl2583.c
>> +++ b/drivers/iio/light/tsl2583.c
>> @@ -858,7 +858,7 @@ static int tsl2583_probe(struct i2c_client *clientp,
>>   					 TSL2583_POWER_OFF_DELAY_MS);
>>   	pm_runtime_use_autosuspend(&clientp->dev);
>>   
>> -	ret = devm_iio_device_register(indio_dev->dev.parent, indio_dev);
>> +	ret = iio_device_register(indio_dev);
>>   	if (ret) {
>>   		dev_err(&clientp->dev, "%s: iio registration failed\n",
>>   			__func__);
>