Re: [PATCH v7 1/6] dt-bindings: ti-lmu: Remove LM3697

From: Dan Murphy
Date: Mon Sep 17 2018 - 11:24:45 EST


On 09/15/2018 03:00 PM, Jacek Anaszewski wrote:
> Hi Pavel.
> On 09/14/2018 11:42 PM, Pavel Machek wrote:
>> Hi!
>>>> You may want to learn more about device tree and/or talk to the device
>>>> tree maintainers. This is an old article.
>>> The article title is "Device trees as ABI". A device tree is defined
>>> in the "*.dts" file that is then compiled to a dtb blob, which
>>> constitutes the ABI. And this ABI should be kept backwards compatible.
>>> What is discussed here is a documentation of bindings, i.e. according
>>> to ePAPR: "requirements for how specific types and classes of devices
>>> are represented in the device tree".
>>> >From the bindings documented in the
>>> Documentation/devicetree/bindings/mfd/ti-lmu.txt only
>>> ti,lm3532-backlight is used in the mainline dts file
>>> (arch/arm/boot/dts/omap4-droid4-xt894.dts).
>>> Having the above it seems that there is no risk of breaking any
>>> users.
>> DTBs and bindings are supposed to be portable between operating
>> systems. You are right there are no _mainline_ _Linux_ users.
> No mainline users means no users we should care of.
> Other people also don't care - see patch [0].
>>>> NAK on this patch. I see that this binding has problems, but
>>>> introducing different binding for subset of devices is _not_ a fix.
>>>>>> What about the multi function devices? They should have same binding.
>>>>> The MFD devices defined are not in contention here only the SFD.
>>>> I'd like to see common solutions for SFD and MFD, as the hardware is
>>>> similar, and that includes the code. Having code that is easier to
>>>> maintain is important, and having many drivers are harder to maintain
>>>> than one driver.
>>>> Milo's code looks better than yours in that regard. I disagree about
>>>> Milo's code being "nightmare" to modify, and care about "easy to
>>>> maintain" more than "binary size".
>>> Easy to maintain will be a dedicated LED class driver.
>> You mean, 3 dedicated LED class drivers and 3 MFD drivers with LED
>> parts? We'll need complex driver anyway, and I'd really like to have
>> just one.
> In the LED subsystem we can wrap common functionalities
> into a library object. MFD driver will be able to reuse it then.

I am currently working on that code now. I expect a RFC on this this week.


> [0]

Dan Murphy