Re: [PATCH v3 0/5] iio: adc: ad4080: add support for AD4880 dual-channel ADC

[Jonathan Cameron]

On Fri, 13 Feb 2026 16:47:32 +0200
Antoniu Miclaus <antoniu.miclaus@xxxxxxxxxx> wrote:

> Add support for the AD4880, a dual-channel 20-bit 40MSPS SAR ADC from
> the same family as AD4080.
> 
> The AD4880 has two independent ADC channels, each with its own SPI
> configuration interface and LVDS data output. The driver uses
> spi_new_ancillary_device() for the second channel's SPI and requires
> two io-backend instances for the data interfaces.
> 
> This series includes:
>   - SPI core fix to allow ancillary devices to share parent's chip selects
>   - New devm_spi_new_ancillary_device() managed helper
>   - Refactored devm_iio_backend_get_by_index() for multi-channel backend lookup
>   - DT bindings update for AD4880
>   - Driver support for AD4880
> 
> Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ad4880.pdf

Just to be clear on status, this set is held on resolving Andy's
observation (that probably raced with posting this update) that
the SPI core has support for multiple chip select devices and how
this code differs from what that provides.

I haven't looked into this in detail so it may well just be a case
of providing more details on what is going on here vs what the SPI
subsystem supports (which might just be switching all the chip selects
together?)

Jonathan