Hi!

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+		io-channels = <&twl_madc 1>,
+	                      <&twl_madc 10>,
+			      <&twl_madc 12>;
+		io-channel-names = "temp",
+		                   "ichg",
+		                   "vbat";
+	};

Rather than just making platform_data into device tree properties..

Can't you hide the these custom properties behind the compatible flag?

You can initialize that data in the driver based on the compatible
flag and the match data.

This makes sense if you can group things to similar configurations.

Maybe I have not completely understood your proposal.

Do you mean to go back to have big parameter tables for each device/battery
combination in the driver code and the compatible flag (e.g. compatible = ?board17?)
chooses the right data set for the charging map and channels?

If you can somehow group them, then yes. Not for every board if there
are many of them naturally.
 

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I thought this is what the DT was introduced for - to have the same driver 
code but adapt to different boards depending on hardware variations.

Yeah but you also need to consider the issues related to introducing
new device tree properties. The device tree properties introduced
should be generic where possible.

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And batteries have very different characteristics and vary between devices?

Right. Maybe that has been already agreed on to use capacity-uah for
batteries in general? In that case I have not problem with that as
it's a generic property :)
 

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The charging maps are depending on the battery type connected to the twl4030
and which madc channel is which value is also a little hardware dependent
(although the twl4030 doesn?t give much choice).

Just to consider alternatives before introducing driver specific
property for the maps.. Maybe here you could have few different type
of maps and select something safe by default? Of course it could be this
is higly board specific, I think some devices may be able to run below
3.3V for example..

As I explained in some other mail, those tables should not be
neccessary at all. They can be computed from li-ion characteristics
and internal resistance, and assumed current during charge and
discharge.

Running below 3.3V.. not really. At that point, the battery is really
_empty_, and voltage is going down really really fast.

Plus, you are damaging the battery at that point.
									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html