On Mon, Oct 29, 2018 at 9:10 PM Quentin Schulz <quentin.schulz@xxxxxxxxxxx> wrote: > > Hi Jonathan, > > On Sun, Oct 28, 2018 at 03:40:11PM +0000, Jonathan Cameron wrote: > > On Wed, 24 Oct 2018 08:56:33 -0500 > > Rob Herring <robh@xxxxxxxxxx> wrote: > > > > > On Tue, 23 Oct 2018 21:53:23 +0300, Oskari Lemmela wrote: > > > > The AXP803 ADC is compatible with AXP813 ADC, but add > > > > specific compatible for it. > > > > > > > > Signed-off-by: Oskari Lemmela <oskari@xxxxxxxxxxx> > > > > --- > > > > Documentation/devicetree/bindings/iio/adc/axp20x_adc.txt | 2 ++ > > > > 1 file changed, 2 insertions(+) > > > > > > > > > > Reviewed-by: Rob Herring <robh@xxxxxxxxxx> > > > > This doesn't seem to have any dependencies with the other patches > > so applied to the togreg branch of iio.git and pushed out as testing > > for the autobuilders to ignore. However I am a little curious to know > > why we would add the ID and then not use it (that I can see)? > > > > Sometimes with Allwinner (and X-Powers), two IPs seem identical until we > discover something that is slightly different. When this happens, we > have to add a compatible to differentiate both. However, we would also > need to change the Device Tree to change the compatible. We would need > to handle the driver behaviour for both Device Trees. > > So better anticipate a possible difference so that we don't have to do > some hacks in the driver to handle the device correctly. > > As always, Chen-Yu or Maxime may know better so I'm just stating what I > seem to recall. With Allwinner stuff (X-Powers included), sometimes the documents are incomplete or have errors. We tend to add a model-specific compatible just in case things turn out not to be so compatible, unless someone has triple-checked everything, documents and actual hardware included. However we don't actually document these, so this patch isn't strictly needed. (I suppose this might annoy the device tree binding maintainers.) ChenYu
