linux-kernel - Re: [PATCH v6 00/8] Renesas RZ/A1 pin and gpio controller

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Message-ID: <CAMuHMdXCT_Zw8bdzE0SbcDwwqyzKQwxtcyKHL18q2n7eLMaESw@mail.gmail.com>
Date:   Wed, 28 Jun 2017 19:36:15 +0200
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Jacopo Mondi <jacopo+renesas@...ndi.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Chris Brandt <chris.brandt@...esas.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Russell King <linux@...linux.org.uk>,
        Dong Aisheng <aisheng.dong@....com>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v6 00/8] Renesas RZ/A1 pin and gpio controller

Hi Linus,

On Mon, Jun 26, 2017 at 10:45 AM, Geert Uytterhoeven
<geert@...ux-m68k.org> wrote:
> On Thu, Jun 22, 2017 at 4:54 PM, Jacopo Mondi <jacopo+renesas@...ndi.org> wrote:
>>    this is 6th round of RZ/A1 pin controller patch series.
>>
>> Where did we stop: discussion from pin controller driver shifted toward two
>> new generic pin configuration properties I added to the previous series
>> (bi-directional and output-enable).
>>
>> After a really long discussion, we decided to go for handling internally all
>> bi-directional use cases, making the generic property not a requirement for the
>> series. Interestingly, we recently found out the number of pins actually
>> requiring this flag is less (~half) than what reported by the processor manual,
>> so we could have handled these internally from day one :(
>>
>> We also now manage internally pins requiring IO direction specified in software
>> even when configured in alternate function mode (SWIO mode). Most of them are
>> handled by the driver, some of them have to come from DTS as the user can freely
>> select if they have to be inputs or outputs. For those pins, and after another
>> discussion involving NXP developers, we decided to use input-enable and
>> output-enable properties. I have just sent a patch to add output-enable to the
>> generic pin configuration properties, but it is currently under discussion.
>>
>> However, none of the pins currently configured by mainline DTS require those
>> properties to be specified, so I have dropped in this driver any dependency on
>> output-enable property, and I'm using instead the already in place
>> PIN_CONFIG_OUTPUT one. Once output-enable will eventually be accepted, we can
>> update the driver to make use of it, but since there are no use cases for that
>> at the moment, it makes not too much sense holding this series back for that.
>>
>> The total memory occupation we were so worried about of bi-directional and swio
>> pin tables is now around 100 bytes, because of how the number of pins actually
>> needing those flags has  reduced and because of how we have arranged the
>> tables using bitfield structures (credits to Geert here).
>>
>> Having cleared out dependencies on new pin configuration properties and having
>> made configuration flags a driver specific issue, I hope this version can be
>> accepted and land in forthcoming pull request for Renesas PFC updates from
>> Geert, pending some feedback from the linux-gpio community.
>
> If this is OK for you, I'd like to include the first 3 patches (plus a small
> fix I received offline from Chris Brandt[*]) in my final pull request of
> sh-pfc for v4.13 (which I have been postponing in anticipation of this driver).

And so I did. Queued in sh-pfc-for-v4.13, pull request sent.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds