linux-kernel - Re: [PATCH 4/4] gpio/rockchip: fetch deferred output settings on probe

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Date:   Sat, 18 Sep 2021 02:00:27 +0200
From:   Heiko Stübner <heiko@...ech.de>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Jianqun Xu <jay.xu@...k-chips.com>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        "open list:ARM/Rockchip SoC..." <linux-rockchip@...ts.infradead.org>,
        linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] gpio/rockchip: fetch deferred output settings on probe

Hi Linus,

Am Samstag, 18. September 2021, 01:38:08 CEST schrieb Linus Walleij:
> On Tue, Sep 14, 2021 at 12:49 AM Heiko Stuebner <heiko@...ech.de> wrote:
> 
> > Fetch the output settings the pinctrl driver may have created
> > for pinctrl hogs and set the relevant pins as requested.
> >
> > Fixes: 9ce9a02039de ("pinctrl/rockchip: drop the gpio related codes")
> > Signed-off-by: Heiko Stuebner <heiko@...ech.de>
> 
> Since this patch depends on patch 4/4 I applied this to the pinctrl
> tree as well.
> 
> I still think this looks a bit kludgy but can't think of anything better
> right now and we need a fix for the problem so this goes in.
> 
> But we need to think of something better,

I'm all ears :-) . And yes I do agree with you that this is not very
elegant right now.

The issue is that the pinconf part for PIN_CONFIG_OUTPUT is actually
using the gpio controller to realize this setting. So when this ends up
in a pinctrl-hog, stuff explodes while probing the first pinctrl part.

I guess one way would be to somehow only do the pinctrl-hogs
_after_ all parts have probed.

Thinking about this, the component framework may be one option?
And then adding a pinctr-register / init+enable variant where the
pinctrl hogs can be aquired separately, not as part of pinctrl_enable?

Or maybe I'm thinking way too complex and a way easier solution
is around the corner ;-) .

Heiko