Re: [PATCH v2 0/2] iio: orientation: hid-sensor-rotation: fix quaternion alignment

[David Lechner <dlechner@baylibre.com>]

On 3/2/26 6:32 AM, Nuno Sá wrote:
> On Mon, 2026-03-02 at 10:58 +0200, Andy Shevchenko wrote:
>> On Sat, Feb 28, 2026 at 02:02:21PM -0600, David Lechner wrote:
>>> The main point of this series is to fix a regression reported in
>>> hid-sensor-rotation where the alignment of the quaternion field in the
>>> data was inadvertently changed from 16 bytes to 8 bytes. This is an
>>> unusually case (one of only 2 in the kernel) where the .repeat field of
>>> struct iio_scan_type is used and we have such a requirement. (The other
>>> case uses u16 instead of u32, so it wasn't affected.)
>>>
>>> To make the reason for the alignment more explicit to future readers,
>>> we introduce a new macro, IIO_DECLARE_QUATERNION(), to declare the
>>> array with proper alignment. This is meant to follow the pattern of
>>> the similar IIO_DECLARE_BUFFER_WITH_TS() macro.
>>
>> Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
>>
>> But this is in conflict with the other hack-patch in another series.
>> I'm a bit lost what patch 2 fixes here and that hack-patch fixes
>> in the same driver. Shouldn't survive only one?
> 
> +1.
> 
> I see this is older so should we only look at the other series?
> 
> - Nuno Sá

They are fixing two separate bugs.

This bug (which is a recent regression) is that the size of the struct is
wrong. It is supposed to be 32 bytes, but a recent change make it only 24.
This causes iio_push_to_buffers_with_ts() to write over data past the end
of the struct.

The other bug (which has been a bug for 6 years) is that the the timestamp
is in the wrong place. That patch also has an effect of making the struct
the right size, but that is only a side-effect.

So yes, I should have mentioned that in the cover letter that this series
should probably be applied first since it is the worse bug. And it looks
like I'll be doing a v2 of the other series anyway, so I can properly rebase
it and declare the dependency.