Re: [PATCH v2] iio: adc: ad7606_spi: add offload scan mask check

[Andy Shevchenko]

On Fri, May 2, 2025 at 6:42 PM David Lechner <dlechner@xxxxxxxxxxxx> wrote:
>
> Validate the scan mask when SPI offloading is being used.
>
> Since this family of ADCs is simultaneous sampling, there isn't a way
> to selectively disable channels when reading sample data. (Technically,
> AD7616 has a sequencer so could have some control, but that is for

so it could

> another day).
>
> For "regular" IIO triggered buffer reads, this isn't a problem and the
> IIO core will demux the data and ignore data from disabled channels.
> However, since SPI offloading is done completely in hardware, we don't
> have a way to do the same. So before this patch, if less than all
> channels were enabled, the data would be misplaced in the buffer.
>
> By adding a check in update_scan_mode, we can fail to enable the buffer
> instead of having bad data returned to userspace.

Reviewed-by: Andy Shevchenko <andy@xxxxxxxxxx>

-- 
With Best Regards,
Andy Shevchenko