linux-kernel - Re: [PATCH v3 04/14] GPIO: Add gpio-ingenic driver

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Date:   Fri, 3 Feb 2017 14:58:50 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Paul Cercueil <paul@...pouillou.net>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Ralf Baechle <ralf@...ux-mips.org>,
        Ulf Hansson <ulf.hansson@...aro.org>,
        Boris Brezillon <boris.brezillon@...e-electrons.com>,
        Thierry Reding <thierry.reding@...il.com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Maarten ter Huurne <maarten@...ewalker.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Paul Burton <paul.burton@...tec.com>,
        "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>,
        Linux MIPS <linux-mips@...ux-mips.org>,
        "linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
        "linux-mtd@...ts.infradead.org" <linux-mtd@...ts.infradead.org>,
        "linux-pwm@...r.kernel.org" <linux-pwm@...r.kernel.org>,
        "linux-fbdev@...r.kernel.org" <linux-fbdev@...r.kernel.org>,
        James Hogan <james.hogan@...tec.com>
Subject: Re: [PATCH v3 04/14] GPIO: Add gpio-ingenic driver

On Tue, Jan 31, 2017 at 4:29 PM, Paul Cercueil <paul@...pouillou.net> wrote:
> Le 2017-01-31 15:20, Linus Walleij a écrit :
>
>>> + of_property_read_u32(dev->of_node, "base", &jzgc->gc.base);
>>
>>
>> Remove this. Dynamic allocation should be fine, if you're using the
>> new userspace ABI like tools/gpio/* or libgpiod and only that and
>> in-kernel
>> consumers, dynamic numbers are just fine.
>
>
> The problem is that the QI_LB60 board code still have a lot of references
> to global GPIO numbers. Just grep for JZ_GPIO_PORT in
> arch/mips/jz4740/board-qi_lb60.c to see what I mean...

OK I understand we might need a compromise here to get the code moving.

But we need to keep it out of the device tree.

I think it's better to put a base table relative to the memory base in
the driver in that case:

unsigned int gpio_global_base;

switch (memory_base_address) {
case 0x41000000:
    gpio_global_base = 0x00;
    break;
case 0x42000000:
    gpio_global_base = 0x20;

(...)

etc. (Those are not your base addresses but you get the idea).

Include a few comments like:

/*
 * DO NOT EXPAND THIS: FOR BACKWARD GPIO NUMBERSPACE
 * COMPATIBIBILITY ONLY: WORK TO TRANSITION CONSUMERS TO
 * USE THE GPIO DESCRIPTOR API IN <linux/gpio/consumer.h> INSTEAD.
 */

Then I'll be happy :)

Yours,
Linus Walleij