From mboxrd@z Thu Jan 1 00:00:00 1970 From: Linus Walleij Subject: Re: [PATCH v1 1/2] pinctrl: tegra: Move drivers registration to arch_init level Date: Fri, 3 Aug 2018 19:24:56 +0200 Message-ID: References: <20180802111144.12512-1-digetx@gmail.com> <20a52a0461e32e776e526171c250551a@agner.ch> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Return-path: In-Reply-To: <20a52a0461e32e776e526171c250551a@agner.ch> Sender: linux-kernel-owner@vger.kernel.org To: Stefan Agner Cc: Dmitry Osipenko , "thierry.reding@gmail.com" , Jon Hunter , Marcel Ziswiler , linux-tegra@vger.kernel.org, "open list:GPIO SUBSYSTEM" , "linux-kernel@vger.kernel.org" List-Id: linux-gpio@vger.kernel.org On Thu, Aug 2, 2018 at 1:31 PM Stefan Agner wrote: > A while back at least using those init lists were not well received even > for GPIO/pinctrl drivers: > > https://lore.kernel.org/lkml/CACRpkdYk0zW12qNXgOstTLmdVDYacu0Un+8quTN+J_azOic7AA@mail.gmail.com/T/#mf0596982324a6489b5537b0531ac5aed60a316ba You shouldn't listen too much to that guy he's not trustworthy. > I still think we should make an exception for GPIO/pinctrl and use > earlier initcalls. Platform GPIO/pinctrl drivers provide basic > infrastructure often used by many other drivers, we want to have them > loaded early. It avoids unnecessary EPROBE_DEFER and hence probably even > boots faster. When we have the pin control and GPIO at different initlevels it makes me uneasy because I feel we have implicit init dependencies that seem more than a little fragile. My recent thinking has involved the component method used in DRM drivers such as drivers/gpu/drm/vc4/vc4_drv.c where a few different component subdrivers are linked together at bind time (not probe time!) into a master component. Rob was no big fan of this but the DRM people like it and I was thinking to make a try at it. This way we could at least probe and bind the pin control and GPIO drivers at the *same* initlevel and express the dependencies between them somewhat. > This should definitely go in, at least as a stop gap solution. Agreed. (And patch applied.) Yours, Linus Walleij