From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7B084C433E0 for ; Thu, 7 Jan 2021 10:37:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2D2D72313B for ; Thu, 7 Jan 2021 10:37:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726541AbhAGKhe (ORCPT ); Thu, 7 Jan 2021 05:37:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48376 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726822AbhAGKhe (ORCPT ); Thu, 7 Jan 2021 05:37:34 -0500 Received: from mail-lf1-x129.google.com (mail-lf1-x129.google.com [IPv6:2a00:1450:4864:20::129]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 65C5DC0612F5 for ; Thu, 7 Jan 2021 02:36:53 -0800 (PST) Received: by mail-lf1-x129.google.com with SMTP id o17so13496525lfg.4 for ; Thu, 07 Jan 2021 02:36:53 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=nFfGlH5hXwbuaYUBsZBOfb6uPO2NVxjByxMtfTjhGZ4=; b=OvqgYG5GfLnUWMDVt7fwGeXDObUORXSH+iOnzildwroxSkzsO/YzNGjGRmbA7SYLPV x8nxD4BNfcPV6O2VQ+H2sXHcBagqd3oT5/cSajzlk/tGpxe5DIt7+J21on5fSDkjwPBE je997Wma6HpOQpxEn74aFuJskTFroRdqupPPP1RoadoStwgVfKrRXLnEMJg0nXKpjFb+ thRNzVOAUQJk/fJDOvb08chmTAZOJx1FawgClXTTJ56ubJsL96r4ruCXLe076I2FlDey l3Uyye8Vb8lv6IQvas953SreICCTijWTJEp7H8IMUn+A6U4qpQbflPXJ5xuWSeugoT+N nk3A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=nFfGlH5hXwbuaYUBsZBOfb6uPO2NVxjByxMtfTjhGZ4=; b=KkeWZWB9hS0JZM6l3/BmIT099ETGPdwdrv2D+6EZ7kt+aKr6HLqE792MWSvP9lJISe JhT/APg0tOWWUQYUnnRfci0di2Jh5KHqz8Pnnu9Vt1ChLtP/jataoNfYtD1P2JyzZhJR mOmfnVKRarRvTJq1isA7+E/Srq88FWnDII9dUMYAVUINPoJvjHqOCkbyMJ5uBEd9D6l7 mYk8qnByRFaEeGaIrgdaFUiOi1VRiR0Aom0GpnHPUmFzwuvD3xIzhaOpcUnnlU8L8mic vziHyDahQl/rXYcjBASFFnvQafcLUmc2OtPOBNzZsgORUsNO1ilwYi8QLVhYbl59QcIh kclg== X-Gm-Message-State: AOAM533OfScnBAVxQdGCp+6FuipNxVq6DJUnNu9z3eJxG20BaafVP8lu Io3upst9OZ+E1ATceQ/++1wV6LrUqCwe/HxnpfcsFQ== X-Google-Smtp-Source: ABdhPJyfAnEcXOXLY4xTmk1dpmDhjGS0UtzXooi8t4a+PiMBAIP9rKiFMYgT/OAB+huqAHSbFRl1FEjWiqnjm8x/c0g= X-Received: by 2002:a05:6512:74e:: with SMTP id c14mr4116363lfs.529.1610015811936; Thu, 07 Jan 2021 02:36:51 -0800 (PST) MIME-Version: 1.0 References: <20201004162908.3216898-1-martin.blumenstingl@googlemail.com> <20201004162908.3216898-4-martin.blumenstingl@googlemail.com> In-Reply-To: From: Linus Walleij Date: Thu, 7 Jan 2021 11:36:40 +0100 Message-ID: Subject: Re: [RFC PATCH 3/3] gpio: ej1x8: Add GPIO driver for Etron Tech Inc. EJ168/EJ188/EJ198 To: Martin Blumenstingl Cc: Bjorn Helgaas , linux-usb , linux-pci , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , "open list:GPIO SUBSYSTEM" , Rob Herring , Bartosz Golaszewski , "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-gpio@vger.kernel.org On Wed, Jan 6, 2021 at 4:17 PM Martin Blumenstingl wrote: > > > unfortunately this means that xhci-pci now depends on xhci-pci-etron. > > > for xhci-pci-renesas this is fine (I think) because that part of the > > > code is needed to get the xHCI controller going > > > but for xhci-pci-etron this is a different story: the GPIO controller > > > is entirely optional and only used on few devices > > > > I might be naive but should it not be the other way around? > > That xhci-pci-etron is dependent on xhci-pci? I imagine > > it would be an optional add-on. > > the only way to achieve this that I can think of is to basically have > xhci-pci-etron implement it's own pci_driver and then call > xhci_pci_probe, xhci_pci_remove, etc. > but then it depends on the driver load order if the GPIO controller is exposed > > what structure did you have in mind to achieve this? Something that is compiled and called conditionally with stubs in the local .h file. Kconfig: config FOO tristate "Main matter" config FOO_ADD_ON tristate "Optional on" depends on FOO Makefile: obj-$(CONFIG_FOO) += foo.o obj-$(CONFIG_FOO_ADD_ON) += foo-add-on.o foo.h: struct foo { ... }; #if IS_ENABLED(CONFIG_FOO_ADD_ON) int foo_add_on_init(struct foo *); #else /* No CONFIG_FOO_ADD_ON */ static int foo_add_on_init(struct foo *) { return 0; } #endif foo.c: #include "foo.h" ret = foo_add_on_init(foo); (...) foo-add-on.c: int foo_add_on_init(struct foo *) { (...) } EXPORT_SYMBOL_GPL(foo_add_on_init); > > Make sure the etron part is an additional module that can be > > loaded after xhci-pci. > > my approach from above unfortunately would not achieve this > so if you have an idea how to achieve this (or have any other driver > in mind that I can use as reference, even if not related to > GPIO/USB/PCI then please let me know) See per above. I don't see any problem with this, it will be an additional module that does not feature a probe() call and device driver bind. I think it is also possible to link both files into the same object if the optional add on is enabled, so it is part of the main module when modprobing. The foo.h stubs are still needed, then the binary will just be smaller if the add-on is not enabled. There are solutions like this in the kernel, I just don't remember one right now so grep around. Yours, Linus Walleij