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=-13.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 4376FC433F5 for ; Mon, 6 Sep 2021 07:54:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 29F4E60F9E for ; Mon, 6 Sep 2021 07:54:04 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240322AbhIFHzH (ORCPT ); Mon, 6 Sep 2021 03:55:07 -0400 Received: from mail-vs1-f46.google.com ([209.85.217.46]:37571 "EHLO mail-vs1-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240117AbhIFHzF (ORCPT ); Mon, 6 Sep 2021 03:55:05 -0400 Received: by mail-vs1-f46.google.com with SMTP id i23so4844872vsj.4; Mon, 06 Sep 2021 00:54:01 -0700 (PDT) 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=Xon8B2SCZnddw6P26dcLHhHXVXDY1KEqtTk0C4c5WI8=; b=szQNWjj+G0hWiwJFuk3suUNWJ8gBJ9K2ol/zZXrWYqQFnfgblr/8JH6UBAq41eYow7 lr8I02tgJiLcQ/ov6OliWak13u7wlrFIUT4LHHovHKfaOCbJsSGaqw/eWGOJf5w/rkKb Ml6fr81oL/XVQwJw8lH3NACVt8Y24ACGlbq0/qy0StG2oi3RzlNVyDVhV8L/9Wj6YFWz gawhT1afjrWrw2YqeDB7TyBeuXHoIc/BZPF9P1arb/9n7JxNZV7+wrIfwA9kx7T7UTzm k1gi9LdiwN5V0q8Q8kVV50v4a0MmIBwdBIMrlLExNLuIOZxYCHKIBvacxbNq2ba+REV0 H5AQ== X-Gm-Message-State: AOAM531AZDZY74FmS15CWyM2OdnhlbBVO2mxzuGi6ZbzVihj0cju5rvL q6FFIpaXQiqQ1uh/qqIUQexbERYHyD9n09CMkLg= X-Google-Smtp-Source: ABdhPJwiJLO1eun4znmfPQAmEZ02gXfXHVnSn4DLHuIKjjf0oWm84/rA+gjdhs/7qH0Ulg2tAq6+9LjizZw+NnURxdw= X-Received: by 2002:a67:cb0a:: with SMTP id b10mr4993974vsl.9.1630914840618; Mon, 06 Sep 2021 00:54:00 -0700 (PDT) MIME-Version: 1.0 References: <20210904000543.2019010-1-saravanak@google.com> <20210904000543.2019010-2-saravanak@google.com> In-Reply-To: <20210904000543.2019010-2-saravanak@google.com> From: Geert Uytterhoeven Date: Mon, 6 Sep 2021 09:53:49 +0200 Message-ID: Subject: Re: [PATCH v3 1/2] drivers: bus: simple-pm-bus: Add support for probing simple bus only devices To: Saravana Kannan Cc: Russell King , Neil Armstrong , Magnus Damm , Tony Lindgren , Catalin Marinas , Will Deacon , Damien Le Moal , Ulf Hansson , Rob Herring , Android Kernel Team , Linux ARM , Linux Kernel Mailing List , linux-oxnas@groups.io, Linux-Renesas , "open list:TI ETHERNET SWITCH DRIVER (CPSW)" , linux-riscv , Lee Jones Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Saravana, Thanks for your patch! CC linux-pm, Lee (mfd) On Sat, Sep 4, 2021 at 2:05 AM Saravana Kannan wrote: > fw_devlink could end up creating device links for bus only devices. > However, bus only devices don't get probed and can block probe() or > sync_state() [1] call backs of other devices. To avoid this, probe these > devices using the simple-pm-bus driver. > > However, there are instances of devices that are not simple buses (they > get probed by their specific drivers) that also list the "simple-bus" > (or other bus only compatible strings) in their compatible property to > automatically populate their child devices. We still want these devices > to get probed by their specific drivers. So, we make sure this driver > only probes devices that are only buses. Note that this can also be the case for buses declaring compatibility with "simple-pm-bus". However, at the moment, none of such device nodes in upstream DTS files have device-specific drivers. > [1] - https://lore.kernel.org/lkml/CAPDyKFo9Bxremkb1dDrr4OcXSpE0keVze94Cm=zrkOVxHHxBmQ@mail.gmail.com/ > Signed-off-by: Saravana Kannan > Tested-by: Saravana Kannan > --- a/drivers/bus/simple-pm-bus.c > +++ b/drivers/bus/simple-pm-bus.c > @@ -13,11 +13,26 @@ > #include > #include > > - > static int simple_pm_bus_probe(struct platform_device *pdev) > { > - const struct of_dev_auxdata *lookup = dev_get_platdata(&pdev->dev); > - struct device_node *np = pdev->dev.of_node; > + const struct device *dev = &pdev->dev; > + const struct of_dev_auxdata *lookup = dev_get_platdata(dev); > + struct device_node *np = dev->of_node; > + const struct of_device_id *match; > + > + match = of_match_device(dev->driver->of_match_table, dev); > + > + /* > + * These are transparent bus devices (not simple-pm-bus matches) that > + * have their child nodes populated automatically. So, don't need to > + * do anything more. > + */ > + if (match && match->data) { > + if (of_property_match_string(np, "compatible", match->compatible) == 0) Does this work as expected? Having multiple compatible values in a device node does not guarantee there exist a separate driver for any of the device-specific compatible values. > + return 0; > + else > + return -ENODEV; So if we get here, as both branches use "return", we skip the pm_runtime_enable() and of_platform_populate() below: - of_platform_populate() is handled for these buses by of_platform_default_populate(), so that's OK, - I'm wondering if any of the simple-mfd sub-devices use Runtime PM, but currently fail to save power because pm_runtime_enable() is never called for the MFD container, just like with simple-bus... > + } > > dev_dbg(&pdev->dev, "%s\n", __func__); > > @@ -31,14 +46,25 @@ static int simple_pm_bus_probe(struct platform_device *pdev) > > static int simple_pm_bus_remove(struct platform_device *pdev) > { > + const void *data = of_device_get_match_data(&pdev->dev); > + > + if (data) > + return 0; > + > dev_dbg(&pdev->dev, "%s\n", __func__); > > pm_runtime_disable(&pdev->dev); > return 0; > } > > +#define ONLY_BUS ((void *) 1) /* Match if the device is only a bus. */ > + > static const struct of_device_id simple_pm_bus_of_match[] = { > { .compatible = "simple-pm-bus", }, > + { .compatible = "simple-bus", .data = ONLY_BUS }, > + { .compatible = "simple-mfd", .data = ONLY_BUS }, > + { .compatible = "isa", .data = ONLY_BUS }, #ifdef CONFIG_ARM_AMBA ? > + { .compatible = "arm,amba-bus", .data = ONLY_BUS }, > { /* sentinel */ } This is now (almost[*]) the same as of_default_bus_match_table[] in drivers/of/platform.c. Perhaps it can be shared? [*] Especially if "simple-pm-bus" and "simple-bus" would be treated the same. > }; > MODULE_DEVICE_TABLE(of, simple_pm_bus_of_match); Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds