Re: [BUG] iio: imu: inv_icm42600: read temperature, Invalid Argument

[David Lechner <dlechner@baylibre.com>]

On 7/7/25 9:42 AM, Sean Nyekjaer wrote:
> Hi,
> 
> I'm having some weird issues with reading the temperature of the icm42605.
> Kernel version: 6.16.0-rc5
> 
> # cat /sys/bus/iio/devices/iio:device2/name
> icm42605-accel
> 
> When reading the temperature I get:
> # cat /sys/bus/iio/devices/iio:device2/in_temp_raw
> cat: read error: Invalid argument
> 
> But if I read from the accelerometer first, I will go better:
> # cat /sys/bus/iio/devices/iio:device2/in_accel_x_raw
> -378
> # cat /sys/bus/iio/devices/iio:device2/in_temp_raw
> 600
> 
> Then after "some" time, I re-read the temperature I recieve
> "Invalid argument" again.
> 
> I have traced the -EINVAL to inv_icm42600_temp_read() because I receive
> INV_ICM42600_DATA_INVALID.
> 

...

> 
> Will the iio core retry a read? If the -EINVAL is returned,
> inv_icm42600_accel_read_raw() is call once more.

No, the core code won't retry, it just passes the error to
userspace. But it does sound like this driver should do a retry
since the datasheet says:

	Invalid Data Generation: FIFO/Sense Registers may contain
	invalid data under the following conditions:
	...
	c) When accel and gyro are enabled with different ODRs.
	In this case, the sensor with lower ODR will generate
	invalid samples when it has no new data

So it could make sense to fsleep() for one ODR period before
attempting to read to ensure data is available - assuming that
is what is actually happening.


> 
> One more thing...
> When I'm removing the module, the kernel prints this:
> inv-icm42600-i2c 1-0068: Runtime PM usage count underflow!

It looks like there is an extra pm_runtime_put() near the
end of inv_icm42600_core_probe().

> 
> I will continue investigate this
> Br,
> Sean