Re: [PATCH] iio: accel: st_accel: Fix invalid mount_matrix on devices without ACPI _ONT method

[Hans de Goede <hdegoede@redhat.com>]

Hi,

On 4/23/23 12:48, Jonathan Cameron wrote:
> On Tue, 18 Apr 2023 14:32:42 +0200
> Marius Hoch <mail@mariushoch.de> wrote:
> 
>> On 16/04/2023 23:24, Hans de Goede wrote:
>>> When apply_acpi_orientation() fails, st_accel_common_probe() will fall back
>>> to iio_read_mount_matrix(), which checks for a mount-matrix device property
>>> and if that is not set falls back to the identity matrix.
>>>
>>> But when a sensor has no ACPI companion fwnode, or when the ACPI fwnode
>>> does not have a "_ONT" method apply_acpi_orientation() was returning 0,
>>> causing iio_read_mount_matrix() to never get called resulting in an
>>> invalid mount_matrix:
>>>
>>> [root@fedora ~]# cat /sys/bus/iio/devices/iio\:device0/mount_matrix
>>> (null), (null), (null); (null), (null), (null); (null), (null), (null)
>>>
>>> Fix this by making apply_acpi_orientation() always return an error when
>>> it did not set the mount_matrix.
>>>
>>> Signed-off-by: Hans de Goede <hdegoede@redhat.com>  
>> Tested, with the LSM303D patches applied, on a Lenovo Yoga Tablet 2 1051-F.
>>
>> Tested-by: Marius Hoch <mail@mariushoch.de>
> 
> Needs a fixes tag:. I think...
> 
> Fixes: 3d8ad94bb175 ("iio: accel: st_sensors: Support generic mounting matrix")

Right, ack for adding that fixes tag.

Regards,

Hans





> 
> actually introduced the issue rather than the patch that added the _ONT support
> 
> Linus, that's one of yours.  Could you also take a glance at this.
> 
> Seems 'obviously' correct but I've been wrong before :)
>>
>>
>>> ---
>>>   drivers/iio/accel/st_accel_core.c | 4 ++--
>>>   1 file changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/iio/accel/st_accel_core.c b/drivers/iio/accel/st_accel_core.c
>>> index 1628b177d0ed..f7b823ebc96b 100644
>>> --- a/drivers/iio/accel/st_accel_core.c
>>> +++ b/drivers/iio/accel/st_accel_core.c
>>> @@ -1291,12 +1291,12 @@ static int apply_acpi_orientation(struct iio_dev *indio_dev)
>>>   
>>>   	adev = ACPI_COMPANION(indio_dev->dev.parent);
>>>   	if (!adev)
>>> -		return 0;
>>> +		return -ENXIO;
>>>   
>>>   	/* Read _ONT data, which should be a package of 6 integers. */
>>>   	status = acpi_evaluate_object(adev->handle, "_ONT", NULL, &buffer);
>>>   	if (status == AE_NOT_FOUND) {
>>> -		return 0;
>>> +		return -ENXIO;
>>>   	} else if (ACPI_FAILURE(status)) {
>>>   		dev_warn(&indio_dev->dev, "failed to execute _ONT: %d\n",
>>>   			 status);  
>>
>