Re: [PATCH v3] dt-bindings: power: supply: bq24735: reverse the polarity of ac-detect

From: Stephen Warren
Date: Thu Dec 15 2016 - 12:32:33 EST

On 12/15/2016 05:21 AM, Peter Rosin wrote:
The ACOK pin on the bq24735 is active-high, of course meaning that when
AC is OK the pin is high. However, all Tegra dts files have incorrectly
specified active-high even though the signal is inverted on the Tegra
boards. This has worked since the Linux driver has also inverted the
meaning of the GPIO. Fix this situation by simply specifying in the
bindings what everybody else agrees on; that the ti,ac-detect-gpios is
active on AC adapter absence.

Signed-off-by: Peter Rosin <peda@xxxxxxxxxx>


This patch is the result of this discussion:

I don't like how it changes the one thing that is seems correct, but
what to do?

I haven't followed this thread so hopefully what I say is relevant. My take is:

If the DT binding is correct or reasonable, keep it.

If the Tegra DTs contain incorrect content, and never worked correctly in this aspect, then fix them. We do need to maintain DT ABI/compatibility, but I believe only with stuff that actually worked correctly. If the DT has a bug, just fix it.

That said, if ti,ac-detect-gpios is describing a host GPIO, then it's entirely arbitrary which polarity it should have, i.e. the polarity is not something specified by the bq24735 HW. In that case, feel free to change either the binding to match the DT or the DT to match the binding. Changing the DT to match the binding might still be better since there could be other users you're not aware of, and they might have written their DT correctly, and you don't want to break them.