linux-kernel - Re: [PATCH v2 0/4] gpio: fix an incorrect lockdep warning

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Date:   Tue, 20 Sep 2016 14:32:25 +0200
From:   Bartosz Golaszewski <bgolaszewski@...libre.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Peter Rosin <peda@...ntia.se>,
        Peter Zijlstra <peterz@...radead.org>,
        Wolfram Sang <wsa@...-dreams.de>,
        Linus Walleij <linus.walleij@...aro.org>,
        Alexandre Courbot <gnurou@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Vignesh R <vigneshr@...com>, Yong Li <yong.b.li@...el.com>,
        Geert Uytterhoeven <geert+renesas@...der.be>,
        Ingo Molnar <mingo@...hat.com>,
        linux-i2c <linux-i2c@...r.kernel.org>,
        linux-gpio <linux-gpio@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 0/4] gpio: fix an incorrect lockdep warning

2016-09-20 13:30 GMT+02:00 Geert Uytterhoeven <geert@...ux-m68k.org>:
> On Tue, Sep 20, 2016 at 12:48 PM, Peter Rosin <peda@...ntia.se> wrote:
>> On 2016-09-20 12:07, Bartosz Golaszewski wrote:
>>> I feel like it's just wrong to set an arbitrary limit on the number of
>>> i2c branches - and this is what the result of this approach would be.
>>
>> What arbitrary limit would that be? The number of lockdep classes
>> can't be *that* limited? Or?
>>
>> I mean one lockdep class per root adapter and one subclass within that
>> class per mux level doesn't sound too bad. How many root adapters do
>> we need to design for?
>
> 'git grep -c i2c@ -- "*dts*"' told me exynos7 has 12 i2c interfaces.
> And as long as I have gpios (pcf8574?), I can add more using i2c-gpio.
> Hence the upper limit is infinity.
>

Agreed. If you add to that dynamic i2c adapters like hid-cp2112 or
greybus-i2c then it makes infinity plus some more.

Best regards,
Bartosz Golaszewski