linux-kernel - Re: [PATCH] pinctrl: msm: Add support for MSM TLMM pinmux

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Message-ID: <51F969A5.5020405@codeaurora.org>
Date:	Wed, 31 Jul 2013 12:46:45 -0700
From:	Hanumant Singh <hanumant@...eaurora.org>
To:	Stephen Warren <swarren@...dotorg.org>
CC:	Linus Walleij <linus.walleij@...aro.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Bjorn Andersson <Bjorn.Andersson@...ymobile.com>,
	"Bird, Tim" <Tim.Bird@...ymobile.com>,
	ext Tony Lindgren <tony@...mide.com>
Subject: Re: [PATCH] pinctrl: msm: Add support for MSM TLMM pinmux

On 7/30/2013 8:59 PM, Stephen Warren wrote:
> On 07/30/2013 06:13 PM, Hanumant Singh wrote:
>> On 7/30/2013 5:08 PM, Stephen Warren wrote:
>>> On 07/30/2013 06:01 PM, Hanumant Singh wrote:
>>>> On 7/30/2013 2:22 PM, Stephen Warren wrote:
>>>>> On 07/30/2013 03:10 PM, hanumant wrote:
>>>>> ...
>>>>>> We actually have the same TLMM pinmux used by several socs of a
>>>>>> family.
>>>>>> The number of pins on each soc may vary.
>>>>>> Also a given soc gets used in a number of boards.
>>>>>> The device tree for a given soc is split into the different boards
>>>>>> that
>>>>>> its in ie the boards inherit a common soc.dtsi but have separate dts.
>>>>>> The boards for the same soc may use different pin groups for
>>>>>> accomplishing a function, since we have multiple i2c, spi uart etc
>>>>>> peripheral instances on a soc. A different instance of each of the
>>>>>> above
>>>>>> peripherals, can be used in different boards, utilizing different
>>>>>> or subset of same pin groups.
>>>>>> Thus I would need to have multiple C files for one soc, based on the
>>>>>> boards that it goes into.
>>>>>
>>>>> The pinctrl driver should be exposing the raw capabilities of the HW.
>>>>> All the board-specific configuration should be expressed in DT. So, the
>>>>> driver shouldn't have to know anything about different boards at
>>>>> compile-time.
>>>>>
>>>> I agree, so I wanted to keep the pin grouping information in DT, we
>>>> already have a board based differentiation of dts files in DT, for the
>>>> same soc.
>>>
>>> That's the opposite of what I was saying. Pin groups are a feature of
>>> the SoC design, not the board.
>>>
>> Sorry I guess I wasn't clear.
>> Right now I have a soc-pinctrl.dtsi containing pin groupings.
>> This will be "inherited" by soc-boardtype.dts.
>> The pinctrl client device nodes in soc-boardtype.dts will point to pin
>> groupings in soc-pinctrl.dtsi that are valid for that particular boardtype.
>> Is this a valid design?
>
> OK, so you have two types of child node inside the pinctrl DT node; some
> define the pin groups the SoC has (in soc.dtsi) and some define pinctrl
> states that reference the pin group nodes and are referenced by the
> client nodes.
>
> That's probably fine. However, I'd still question putting the pin group
> nodes in DT at all; I'm not convinced it's better than just putting
> those into the driver itself. You end up with the same data tables after
> parsing the DT anyway.
>

Any feedback for the rest of the patch?

Thanks
Hanumant

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