Re: [PATCH v3 2/2] iio: imu: st_lsm6dsx: Add ACPI ID SMOCF05 for LSM6DS3TR-C

[Andy Shevchenko]

On Mon, Sep 28, 2026 at 6:29 PM Jared Wuerzburger <jwuerz@xxxxxxxxx> wrote:
>
> On Mon, Sep 28, 2026 at 12:13:17PM +0300, Andy Shevchenko wrote:
> > On Sun, Sep 27, 2026 at 05:05:59PM -0500, Jared Wuerzburger wrote:

...

> > > Both I2C resources describe the same address, and the driver uses the
> > > first one. The vendor-specific SLA0/SLG0 mount matrices are not parsed
> > > here; the accelerometer orientation is handled in userspace through
> > > the systemd hwdb, as for SMOCF00.
> >
> > Hmm... But is that wrong? I mean does ACPI provide the correct data in mount
> > matrix?
>
> Good question, and it made me check more carefully: X and Y are right,
> Z isn't. SLA0 (-1 0 0; 0 -1 0; 0 0 -1) matches the Windows sensor
> convention, which reports the gravity vector (Z = -1g with the screen
> facing up). SLG0 being identity fits that: SLA0's negation is a sign
> convention, not a mounting rotation. With it applied via hwdb,
> auto-rotation on my V3 is correct (that only depends on the X and Y
> signs), but iio-sensor-proxy reports the tilt inverted: "tilted-down"
> with the screen leaning back. With -1 0 0; 0 -1 0; 0 0 1, a plain
> 180 degree rotation about Z, orientation and tilt are both right. That
> means the systemd hwdb entry that went in today [1] has the wrong Z
> sign; the fix is here [2].
>
> So the firmware values can't be used as a mount matrix as they are;
> reading SLA0 like ROTM, as v2 did, would have exported the same wrong
> Z. That's one more reason I'd keep this series to the ID and leave the
> orientation to hwdb, as was done for SMOCF00. If you'd still like the
> firmware data used in the driver, I'm happy to look at it as a
> follow-up, but it would need translating from the Windows convention
> rather than usingit as a mount matrix.

For the starter just summarize above in the commit message in v4. This
will justify usage of hwdb (IIUC the case).

> [1] https://github.com/systemd/systemd/pull/43935
> [2] https://github.com/systemd/systemd/pull/43941

-- 
With Best Regards,
Andy Shevchenko