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=-23.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 4DF71C433FE for ; Tue, 7 Sep 2021 07:02:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3243660F25 for ; Tue, 7 Sep 2021 07:02:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236005AbhIGHDE (ORCPT ); Tue, 7 Sep 2021 03:03:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53470 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235121AbhIGHDD (ORCPT ); Tue, 7 Sep 2021 03:03:03 -0400 Received: from mail-yb1-xb30.google.com (mail-yb1-xb30.google.com [IPv6:2607:f8b0:4864:20::b30]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B06C8C06175F for ; Tue, 7 Sep 2021 00:01:57 -0700 (PDT) Received: by mail-yb1-xb30.google.com with SMTP id q70so17841096ybg.11 for ; Tue, 07 Sep 2021 00:01:57 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=XZ02cCn3jUYwKkL6zF4WdVr12IAXBqByLITg8GOc89U=; b=d93iTWhWZFfJpFHQv7tpLm+6QZsDGz9hKjnedRCRGiLYNluChqhRkJG8SXzFFmOfVW vZm8NbbB/ZNCbEH+OY1q9VJXD0fjaGUX9aQJUUYxnbYUhS2xxPjd7t7qnfh3DD0sXqaq 8eJQxMAUhyqHNspp0CCWfg54DzbMP1WEsE3UY2+m4suxCrOVPaUj4MJvy4uN3GFlxLRi v8Jw1aJXLKQ0fVHK5Kmau8Vb9SBrnQ2b+jGFv+MlkS0Adf5MgCxTQmRtLfXtsw91x17g HBgR7RJrjjEX8i8GP6AKVtWt8Cib2/svkcKBa08Ofa57+WUEXEGVam4avffXdOQ34jYX qFRg== 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=XZ02cCn3jUYwKkL6zF4WdVr12IAXBqByLITg8GOc89U=; b=QIF0bdYHYewAkUFiUaYamoHY4eF7FcuNzLTUtLuesgTOPHVTfcZkXVJY+/lGdkoG8u UoUn+hER33++lhnAQu9iwk0iGAn1cU/9I/VgYQ698f4vMLbssenTu6bi/kSAc5pTsAoX NW+zpBsXivFLPkG+MYGd3f41b8qIeI7pl+jILqrAxMinuD1aHlwgQEgPy8ifNR8a75Ba 7PnWbQW38gorFW7+y/+vMONClCCqqK8ukHdk6vM7rWapK8b+0Ko1yaWyriNgSUnYS/fB 9jJxnM12BtKbKzd81AGpZp06xNj+0ZhIVZ5cyoeTLwkRohsVXTZvOMTH+YkYua8a65eN ADaA== X-Gm-Message-State: AOAM530ViKM3P3OKK+55H7u9nJDCm2cqAAIJMA0J2Num78JiopIH+o7P A3CR5HTFyBPWy5/K17epUCUkpC4F0PDExlJXCV6eDg== X-Google-Smtp-Source: ABdhPJyLhKD3oP2+8EJssMw8N+mu4D4/j9ZXZmiK4Fvt3T9csxsUw9BdjSpamoLn9OyWs207aw/T9vOcGmFBkW99uG4= X-Received: by 2002:a25:b94:: with SMTP id 142mr19856293ybl.508.1630998116640; Tue, 07 Sep 2021 00:01:56 -0700 (PDT) MIME-Version: 1.0 References: <20210904000543.2019010-1-saravanak@google.com> <20210904000543.2019010-2-saravanak@google.com> In-Reply-To: From: Saravana Kannan Date: Tue, 7 Sep 2021 00:01:23 -0700 Message-ID: Subject: Re: [PATCH v3 1/2] drivers: bus: simple-pm-bus: Add support for probing simple bus only devices To: Geert Uytterhoeven 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 On Mon, Sep 6, 2021 at 12:54 AM Geert Uytterhoeven wrote: > > 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. Not sure about mfd, but I want to make sure we don't confuse busses (which are typically added to a class) with these "simple bus" devices that are added to platform_bus. Also if these other buses are actually causing an issue, then then should implement their own stub driver or use try patch[2] if they are added to classes (devices on classes don't probe) [2] - https://lore.kernel.org/lkml/20210831224510.703253-1-saravanak@google.com/ > > > [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. Right, and if they are platform devices that are equivalent to simple-bus (meaning, they don't do anything in Linux and just have their devices populated) we can add those to this list too. > > > + 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... But this doesn't affect simple-mfd though. > > > + } > > > > 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 ? Not needed? If CONFIG_ARM_AMBA isn't enabled, the device wouldn't be created in the first place. > > > + { .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? I wanted this table to be expandable as needed. That's why I'm intentionally not using of_default_bus_match_table[]. > > [*] Especially if "simple-pm-bus" and "simple-bus" would be treated > the same. They are not treated the same way. -Saravana > > > }; > > 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