linux-kernel - Re: [PATCH v3 2/2] iio: gyro: mpu3050-core: fix pm

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Message-ID: <24904c919d52e40bbe6089af54e013d2351296d3.camel@gmail.com>
Date: Mon, 09 Feb 2026 14:27:15 +0000
From: Nuno Sá <noname.nuno@...il.com>
To: Antoniu Miclaus <antoniu.miclaus@...log.com>, Linus Walleij
	 <linusw@...nel.org>, Jonathan Cameron <jic23@...nel.org>, David Lechner
	 <dlechner@...libre.com>, Nuno Sá <nuno.sa@...log.com>, 
 Andy Shevchenko
	 <andy@...nel.org>, linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 2/2] iio: gyro: mpu3050-core: fix pm_runtime error
 handling

On Mon, 2026-02-09 at 14:02 +0200, Antoniu Miclaus wrote:
> pm_runtime_get_sync() does not check its return value, allowing the

I don't want to be too picky but the above is a bit of bad wording :).
pm_runtime_get_sync() indeed returns 'int' so the caller is the one not checking
it. So we have two things happening:

1) We don't want to ignore the return value from the PM API;
2) We don't want to, unconditionally, increment the device usage count and hence pivot to
use pm_runtime_resume_and_get()

- Nuno Sá

> driver to access hardware that may fail to resume. Use
> pm_runtime_resume_and_get() which propagates errors and avoids
> incrementing the usage count on failure.
> 
> In preenable, add pm_runtime_put_autosuspend() on set_8khz_samplerate()
> failure since postdisable does not run when preenable fails.
> 
> Fixes: 3904b28efb2c ("iio: gyro: Add driver for the MPU-3050 gyroscope")
> Reviewed-by: Linus Walleij <linusw@...nel.org>
> Signed-off-by: Antoniu Miclaus <antoniu.miclaus@...log.com>
> ---
> Changes in v3:
> - Rename patch to focus on fix rather than API change
> - Reword commit message
> - Add Fixes: tag
> 
>  drivers/iio/gyro/mpu3050-core.c | 17 +++++++++++++----
>  1 file changed, 13 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/iio/gyro/mpu3050-core.c b/drivers/iio/gyro/mpu3050-core.c
> index ee2fcd20545d..1cc421eb4782 100644
> --- a/drivers/iio/gyro/mpu3050-core.c
> +++ b/drivers/iio/gyro/mpu3050-core.c
> @@ -322,7 +322,9 @@ static int mpu3050_read_raw(struct iio_dev *indio_dev,
>  		}
>  	case IIO_CHAN_INFO_RAW:
>  		/* Resume device */
> -		pm_runtime_get_sync(mpu3050->dev);
> +		ret = pm_runtime_resume_and_get(mpu3050->dev);
> +		if (ret)
> +			return ret;
>  		mutex_lock(&mpu3050->lock);
>  
>  		ret = mpu3050_set_8khz_samplerate(mpu3050);
> @@ -647,12 +649,19 @@ static irqreturn_t mpu3050_trigger_handler(int irq, void *p)
>  static int mpu3050_buffer_preenable(struct iio_dev *indio_dev)
>  {
>  	struct mpu3050 *mpu3050 = iio_priv(indio_dev);
> +	int ret;
>  
> -	pm_runtime_get_sync(mpu3050->dev);
> +	ret = pm_runtime_resume_and_get(mpu3050->dev);
> +	if (ret)
> +		return ret;
>  
>  	/* Unless we have OUR trigger active, run at full speed */
> -	if (!mpu3050->hw_irq_trigger)
> -		return mpu3050_set_8khz_samplerate(mpu3050);
> +	if (!mpu3050->hw_irq_trigger) {
> +		ret = mpu3050_set_8khz_samplerate(mpu3050);
> +		if (ret)
> +			pm_runtime_put_autosuspend(mpu3050->dev);
> +		return ret;
> +	}
>  
>  	return 0;
>  }