Re: [PATCH 1/4] iio: imu: inv_icm42600: sleep before enabling FIFO data

[Andy Shevchenko]

On Fri, Aug 21, 2026 at 12:50:37PM +0000, Jean-Baptiste Maneyrol wrote:
> >From: Andy Shevchenko <andriy.shevchenko@xxxxxxxxx>
> >Sent: Friday, August 21, 2026 13:15
> >On Thu, Aug 20, 2026 at 09:02:37PM +0200, Jean-Baptiste Maneyrol via B4 Relay wrote:

...

> >> +     /* sleep maximum required time */
> >> +     sleep = max(sleep_accel, sleep_temp);
> >> +     if (sleep) {
> >> +             mutex_unlock(&st->lock);
> >> +             msleep(sleep);
> >> +             mutex_lock(&st->lock);
> >> +     }
> >
> >Doesn't sounds correct. Here it breaks the atomicity. Is it a problem?
> >(Imagine a few CPUs doing something with this driver, is any other thread may
> > intervene the flow here?)
> 
> there is no risk here because we are inside the buffer enable function, and
> there is an internal IIO mutex here preventing multiple calls. The driver mutex
> is used to serialize access to the chip, mainly because we have 2 independent
> sensors inside, accelerometer and gyroscope. We need to unlock it here to prevent
> stopping data from the other sensor if it is enabled. For example, when we enable
> gyroscope while accelerometer is running, we don't want to block the chip and
> prevent sending of accelerometer data during 30ms. This is even more important
> because the FIFO can easily overflow at high rates, and there would be data
> loss.
> 
> Hope I'm clear enough in my explanations.

Can we have some (short) comment in the code as well?

...

> >> +     /* sleep maximum required time */
> >> +     sleep = max(sleep_gyro, sleep_temp);
> >> +     if (sleep) {
> >> +             mutex_unlock(&st->lock);
> >> +             msleep(sleep);
> >> +             mutex_lock(&st->lock);
> >> +     }

Ditto.

-- 
With Best Regards,
Andy Shevchenko