Re: [PATCH v6 11/11] iio: adc: hx711: add support for HX710B

[Jonathan Cameron]

On Mon, 4 May 2026 18:52:56 +0300
Andy Shevchenko <andriy.shevchenko@xxxxxxxxx> wrote:

> On Sun, May 03, 2026 at 05:39:40PM +0530, Piyush Patle wrote:
> > Add support for the AVIA HX710B ADC, which shares the HX711 GPIO
> > interface but uses trailing PD_SCK pulses to select the active mode.
> > 
> > Model the HX710B with variant-specific channel tables and IIO info,
> > track the active channel across conversions, and use the fixed gain
> > value when computing scale.
> > 
> > Also update the adjacent Kconfig text, file header, and module
> > description so the driver text matches the newly supported variant.  
> 
> ...
> 
> >  	/*
> >  	 * triggered buffer
> > -	 * 2x32-bit channel + 64-bit naturally aligned timestamp
> > +	 * up to 3x32-bit channels + pad + 64-bit naturally aligned timestamp
> >  	 */
> >  	struct {
> > -		u32 channel[2];
> > +		u32 channel[3];
> > +		u32 pad;
> >  		aligned_s64 timestamp;
> >  	} buffer;  
> 
> Maybe it's obvious to everybody, but me, however I find it difficult to see if
> there is no ABI breakage. Can you add a comment explaining why this is not a
> problem?
> 
I replied in v5 (after this was out :)

It's not actually an ABI breakage, but only because the timestamp doesn't
land where this would make you think it does.  If there are less than 3 channels
enabled it lands 8 bytes in, so on top of channel[2] and the pad.

It is misleading which is why we don't use structures when it is possible to enable
a smaller set of channels and have the ones after them move up in the structure.
David add the stuff to declare buffers for this form - so we should use that.
See v5 reply as I've forgotten what the macro is called again ;)

Jonathan