Re: [RFC PATCH 1/1] iio: dac: add support for ltc2688

[Jonathan Cameron <jic23@kernel.org>]

> >   
> > > > > +               chan->overrange = fwnode_property_read_bool(child,
> > > > > +                                                           "adi,overrange");  
> > > >
> > > > One line?  
> > >
> > > It will pass the 80 col limit. AFAIR, Jonathan prefers to keep it when it
> > > does not hurt readability...  
> > 
> > I believe it will increase readability being located on one line.  
> 
> I mean, this is perfectly aligned with the open "(", so it's a pretty
> normal pattern. Anyways, I'm more than happy to move this into a one
> liner and just use the 100 limit. But let's see what Jonathan has to say
> because I do not want to move back and forward...

Here it happens to be particularly ugly because of the short first parameter,
so I'm fine with a longer line for this one.


> > > > > +       st->regmap = devm_regmap_init(&spi->dev, NULL, st,  
> > > > &ltc2688_regmap_config);
> > > >
> > > > I'm wondering why it's not a regmap SPI?  
> > >
> > > The problem is on the read side... In the first transfer we write the  
> > command/register  
> > > to read, then we need to release the CS pin so that the device  
> > executes the command,  
> > > and only then we read the data. AFAIK, the regmap spi  
> > implementation won't work like  
> > > this. I think CS is kept asserted the whole time...  
> > 
> > I believe it's configurable, no? Like the cs_change flag somewhere.
> > Can you double check?  
> 
> Don't think we can... The read part just calls:
> https://elixir.bootlin.com/linux/latest/source/drivers/base/regmap/regmap-spi.c#L98
> and has no control over the spi transfer bits...

Feature to add then or a custom regmap_bus if you want to keep it in the driver.

J
> 
> - Nuno Sá