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=-9.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 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 8B7D7C433E7 for ; Thu, 15 Oct 2020 14:10:14 +0000 (UTC) Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 0B1FB22248 for ; Thu, 15 Oct 2020 14:10:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="kTzaq7YG" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0B1FB22248 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=merlin.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=NNmma30DWd/yxe1NhEJtszGeY7Ji0jBuIav7ncIiudM=; b=kTzaq7YGlRnpTpdEstIqpiXFm QwIiPtT08UNZeiC/xU7tgFm91fYBq6ajuCX2w5huD7IqGQtdxB7FGqn9v6uza/TRpNNprVGvBMGCt uJ9Hc3SdbtowTSXLIYWsgR0lEC4vMJXADej09KOY67shNyc7kPrmj0+oUlaDOh/+Rxpn4gzgc6cpm 5/wWPGNT/+uJtA9ei4INmYB5I0qgsNEAcbmT5X2HsRfST3Z/ubPXzJO8nAYaB9UWlfVokqtPEdYVs jYAmdCljaG5T2R8jG5L44kfbs20yHoIc2JN++MsLtONSPaOWOHsOzQtjjKJTvHO6sqCIWPesjh6HW bMRaRR+Ug==; Received: from localhost ([::1] helo=merlin.infradead.org) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kT3vw-0001lM-2D; Thu, 15 Oct 2020 14:08:44 +0000 Received: from foss.arm.com ([217.140.110.172]) by merlin.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1kT3vr-0001jL-Uj for linux-arm-kernel@lists.infradead.org; Thu, 15 Oct 2020 14:08:41 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id BF6CC13D5; Thu, 15 Oct 2020 07:08:36 -0700 (PDT) Received: from [10.57.48.76] (unknown [10.57.48.76]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id A16B63F719; Thu, 15 Oct 2020 07:08:34 -0700 (PDT) Subject: Re: fw_devlink on will break all snps,dw-apb-gpio users To: Jisheng Zhang , Saravana Kannan References: <20201014191235.7f71fcb4@xhacker.debian> <20201015120206.41b6a454@xhacker.debian> <20201015161455.744d5041@xhacker.debian> <20201015175231.1a690c21@xhacker.debian> From: Robin Murphy Message-ID: Date: Thu, 15 Oct 2020 15:08:33 +0100 User-Agent: Mozilla/5.0 (Windows NT 10.0; rv:78.0) Gecko/20100101 Thunderbird/78.3.2 MIME-Version: 1.0 In-Reply-To: <20201015175231.1a690c21@xhacker.debian> Content-Language: en-GB X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20201015_100840_102169_F7722068 X-CRM114-Status: GOOD ( 35.35 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , "Rafael J. Wysocki" , Greg Kroah-Hartman , Linus Walleij , LKML , Rob Herring , Frank Rowand , linux-arm-kernel Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On 2020-10-15 10:52, Jisheng Zhang wrote: > On Thu, 15 Oct 2020 01:48:13 -0700 > Saravana Kannan wrote: > >> On Thu, Oct 15, 2020 at 1:15 AM Jisheng Zhang >> wrote: >>> >>> On Wed, 14 Oct 2020 22:04:24 -0700 Saravana Kannan wrote: >>> >>>> >>>> >>>> On Wed, Oct 14, 2020 at 9:02 PM Jisheng Zhang >>>> wrote: >>>>> >>>>> On Wed, 14 Oct 2020 10:29:36 -0700 >>>>> Saravana Kannan wrote: >>>>> >>>>>> >>>>>> >>>>>> On Wed, Oct 14, 2020 at 4:12 AM Jisheng Zhang >>>>>> wrote: >>>>>>> >>>>>>> Hi, >>>>>>> >>>>>>> If set fw_devlink as on, any consumers of dw apb gpio won't probe. >>>>>>> >>>>>>> The related dts looks like: >>>>>>> >>>>>>> gpio0: gpio@2400 { >>>>>>> compatible = "snps,dw-apb-gpio"; >>>>>>> #address-cells = <1>; >>>>>>> #size-cells = <0>; >>>>>>> >>>>>>> porta: gpio-port@0 { >>>>>>> compatible = "snps,dw-apb-gpio-port"; >>>>>>> gpio-controller; >>>>>>> #gpio-cells = <2>; >>>>>>> ngpios = <32>; >>>>>>> reg = <0>; >>>>>>> }; >>>>>>> }; >>>>>>> >>>>>>> device_foo { >>>>>>> status = "okay" >>>>>>> ...; >>>>>>> reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>; >>>>>>> }; >>>>>>> >>>>>>> If I change the reset-gpio property to use another kind of gpio phandle, >>>>>>> e.g gpio expander, then device_foo can be probed successfully. >>>>>>> >>>>>>> The gpio expander dt node looks like: >>>>>>> >>>>>>> expander3: gpio@44 { >>>>>>> compatible = "fcs,fxl6408"; >>>>>>> pinctrl-names = "default"; >>>>>>> pinctrl-0 = <&expander3_pmux>; >>>>>>> reg = <0x44>; >>>>>>> gpio-controller; >>>>>>> #gpio-cells = <2>; >>>>>>> interrupt-parent = <&portb>; >>>>>>> interrupts = <23 IRQ_TYPE_NONE>; >>>>>>> interrupt-controller; >>>>>>> #interrupt-cells = <2>; >>>>>>> }; >>>>>>> >>>>>>> The common pattern looks like the devlink can't cope with suppliers from >>>>>>> child dt node. >>>>>> >>>>>> fw_devlink doesn't have any problem dealing with child devices being >>>>>> suppliers. The problem with your case is that the >>>>>> drivers/gpio/gpio-dwapb.c driver directly parses the child nodes and >>>>>> never creates struct devices for them. If you have a node with >>>>>> compatible string, fw_devlink expects you to create and probe a struct >>>>>> device for it. So change your driver to add the child devices as >>>>>> devices instead of just parsing the node directly and doing stuff with >>>>>> it. >>>>>> >>>>>> Either that, or stop putting "compatible" string in a node if you >>>>>> don't plan to actually treat it as a device -- but that's too late for >>>>>> this driver (it needs to be backward compatible). So change the driver >>>>>> to add of_platform_populate() and write a driver that probes >>>>>> "snps,dw-apb-gpio-port". >>>>>> >>>>> >>>>> Thanks for the information. The "snps,dw-apb-gpio-port" is never used, >>>>> so I just sent out a series to remove it. >>>> >>>> I'd actually prefer that you fix the kernel code to actually use it. >>>> So that fw_devlink can be backward compatible (Older DT + new kernel). >>>> The change is pretty trivial (I just have time to do it for you). >>>> >>> >>> I agree the change is trivial, but it will add some useless LoCs like below. >> >> It's not useless if it preserves backward compatibility with DT. >> >>> I'm not sure whether this is acceptable.So add GPIO and DT maintainers to comment. >>> >>> Hi Linus, Rob, >>> >>> Could you please comment? A simple introduction of the problem: >>> >>> As pointed out by Saravana, "gpio-dwapb.c driver directly parses the child >>> nodes and never creates struct devices for them. If you have a node with >>> compatible string, fw_devlink expects you to create and probe a struct >>> device for it", so once we set fw_devlink=on, then any users of gpio-dwapb >>> as below won't be probed. >>> >>> device_foo { >>> status = "okay" >>> ...; >>> reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>; >>> }; >>> >>> The compatible string "snps,dw-apb-gpio-port" is never used, but it's in >>> the dt-binding since the dw gpio mainlined. I believe the every dw apb >>> users just copy the compatible string in to soc dtsi. So I submit a series >>> to remove the unused "snps,dw-apb-gpio-port" https://lkml.org/lkml/2020/10/14/1186 >>> But this will break Older DT + new kernel with fw_devlink on. Which solution >>> is better? >>> >>> If the following patch is acceptable, I can submit it once 5.10-rc1 is out. >>> >>> thanks >>> >>> diff --git a/drivers/gpio/gpio-dwapb.c b/drivers/gpio/gpio-dwapb.c >>> index 1d8d55bd63aa..b8e012e48b59 100644 >>> --- a/drivers/gpio/gpio-dwapb.c >>> +++ b/drivers/gpio/gpio-dwapb.c >>> @@ -19,6 +19,7 @@ >>> #include >>> #include >>> #include >>> +#include >>> #include >>> #include >>> #include >>> @@ -694,6 +695,10 @@ static int dwapb_gpio_probe(struct platform_device *pdev) >>> } >>> platform_set_drvdata(pdev, gpio); >>> >>> + err = devm_of_platform_populate(dev); >>> + if (err) >>> + goto out_unregister; >>> + >>> return 0; >>> >>> out_unregister: >>> @@ -820,6 +825,25 @@ static struct platform_driver dwapb_gpio_driver = { >>> >>> module_platform_driver(dwapb_gpio_driver); >>> >>> +static const struct of_device_id dwapb_port_of_match[] = { >>> + { .compatible = "snps,dw-apb-gpio-port" }, >>> + { /* Sentinel */ } >>> +}; >>> + >>> +static int dwapb_gpio_port_probe(struct platform_device *pdev) >>> +{ >>> + return 0; >> >> No, I'm not asking to do a stub/dummy probe. Move the stuff you do >> inside device_for_each_child_node{} and dwapb_gpio_add_port() into >> this probe function. Those two pieces of code together are effectively >> "probing" a separate gpio controller for each of the child nodes. So >> just create a real struct device (like we do for every other >> "compatible" DT node) and probe each of them properly using the device >> driver core. > > Then I believe the modifications are non-trivial. Maybe Linus and Rob > can comment which way is better, fix the dts or modify the gpio-dwapb.c. > Personally, I prefer fixing dts, because this doesn't remove or modify > any used properties or compatible string, it just removes the unused > compatible string. You appear to be assuming that: A) There a no consumers of DTBs and DT bindings other than Linux. B) No Linux user ever updates their kernel image without also updating their DTB. I can assure you that, in general, neither of those hold true. Hacking DTs to work around internal implementation details in Linux is rarely if ever a good or even viable idea. Robin. > > Thanks > > >> >>> +} >>> + >>> +static struct platform_driver dwapb_gpio_port_driver = { >>> + .driver = { >>> + .name = "gpio-dwapb-port", >>> + .of_match_table = dwapb_port_of_match, >>> + }, >>> + .probe = dwapb_gpio_port_probe, >>> +}; >>> +module_platform_driver(dwapb_gpio_port_driver); >>> + >>> MODULE_LICENSE("GPL"); >>> MODULE_AUTHOR("Jamie Iles"); >>> MODULE_DESCRIPTION("Synopsys DesignWare APB GPIO driver"); >>> > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel