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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:content-transfer-encoding; bh=GqYzADmVgO8eu/I7MSORCLeA3yiZUEks8OI+aWsxxtY=; b=r9Zx3JLeXPZmB40mi4kZgGLcCuzo/XUdWqq23kl9RhCoJj0XIa446fNLBvG909yvcS RGVQXHnqKHYupC6DKY2Hf+sKeoFWlmgENd8NmxdwMazFmL3JDHJsv5KwrPlJnJBFsIYM YgwuVgcy6k+ASy00kx/uXRNJEgXwBzEUii3xfGoAiQ+OyzAjZr/Djc9FyZIrK9LY7Ewh MdCheBvpGC0O1zgUku3oFFAA7VaMIqvtB7LN1ViMYa3mAYKaas+Jc70U/smqJ6ZPFFav SaUvMSJZeyTqnAgSfhWSaLjzwNq40KG/qq2O3x9H2GepN8MmZajZ8pNNVQ83ImGNcZFV UPzw== X-Gm-Message-State: AOAM532tqh1oKH07yh4hv7R/YmnkYFlJbphK3siGyhrN9roUC+uV7IQV Qmg1Q7bqJ/+N8ClIiCfQDbYGGnot6boA2BFH5hEX0w== X-Google-Smtp-Source: ABdhPJzljeFfuWYYUag/S7LEKjXqAFFjo3NggF/Dt0FdNl6ebzVVtr304gIIC460ujpBvbhrLl8XdcUBuwJp3JtbDV8= X-Received: by 2002:a25:53c9:: with SMTP id h192mr15299393ybb.310.1628294184035; Fri, 06 Aug 2021 16:56:24 -0700 (PDT) MIME-Version: 1.0 References: <20201020072532.949137-1-narmstrong@baylibre.com> <20201020072532.949137-2-narmstrong@baylibre.com> <7hsga8kb8z.fsf@baylibre.com> <87r1hwwier.wl-maz@kernel.org> <7h7diwgjup.fsf@baylibre.com> <87im0m277h.wl-maz@kernel.org> <87sfzpwq4f.wl-maz@kernel.org> <4e98d876-330f-21a4-846e-94e1f01f0eed@baylibre.com> In-Reply-To: <4e98d876-330f-21a4-846e-94e1f01f0eed@baylibre.com> From: Saravana Kannan Date: Fri, 6 Aug 2021 16:55:48 -0700 Message-ID: Subject: Re: [PATCH 1/2] irqchip: irq-meson-gpio: make it possible to build as a module To: Neil Armstrong Cc: Marc Zyngier , Andrew Lunn , Kevin Hilman , Lee Jones , Jerome Brunet , linux-amlogic@lists.infradead.org, linux-arm-kernel , open list , netdev , Android Kernel Team X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210806_165628_226855_697F7527 X-CRM114-Status: GOOD ( 49.81 ) X-BeenThere: linux-amlogic@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-amlogic" Errors-To: linux-amlogic-bounces+linux-amlogic=archiver.kernel.org@lists.infradead.org On Wed, Aug 4, 2021 at 11:31 PM Neil Armstrong wrote: > > Hi Saravana, > > On 04/08/2021 23:47, Saravana Kannan wrote: > > On Wed, Aug 4, 2021 at 11:20 AM Saravana Kannan wrote: > >> > >> On Wed, Aug 4, 2021 at 1:50 AM Marc Zyngier wrote: > >>> > >>> On Wed, 04 Aug 2021 02:36:45 +0100, > >>> Saravana Kannan wrote: > >>> > >>> Hi Saravana, > >>> > >>> Thanks for looking into this. > >> > >> You are welcome. I just don't want people to think fw_devlink is broken :) > >> > >>> > >>> [...] > >>> > >>>>> Saravana, could you please have a look from a fw_devlink perspective? > >>>> > >>>> Sigh... I spent several hours looking at this and wrote up an analysis > >>>> and then realized I might be looking at the wrong DT files. > >>>> > >>>> Marc, can you point me to the board file in upstream that corresponds > >>>> to the platform in which you see this issue? I'm not asking for [1], > >>>> but the actual final .dts (not .dtsi) file that corresponds to the > >>>> platform/board/system. > >>> > >>> The platform I can reproduce this on is described in > >>> arch/arm64/boot/dts/amlogic/meson-sm1-khadas-vim3l.dts. It is an > >>> intricate maze of inclusion, node merge and other DT subtleties. I > >>> suggest you look at the decompiled version to get a view of the > >>> result. > >> > >> Thanks. After decompiling it, it looks something like (stripped a > >> bunch of reg and address properties and added the labels back): > >> > >> eth_phy: mdio-multiplexer@4c000 { > >> compatible = "amlogic,g12a-mdio-mux"; > >> clocks = <0x02 0x13 0x1e 0x02 0xb1>; > >> clock-names = "pclk\0clkin0\0clkin1"; > >> mdio-parent-bus = <0x22>; > >> > >> ext_mdio: mdio@0 { > >> reg = <0x00>; > >> > >> ethernet-phy@0 { > >> max-speed = <0x3e8>; > >> interrupt-parent = <0x23>; > >> interrupts = <0x1a 0x08>; > >> phandle = <0x16>; > >> }; > >> }; > >> > >> int_mdio: mdio@1 { > >> ... > >> } > >> } > >> > >> And phandle 0x23 refers to the gpio_intc interrupt controller with the > >> modular driver. > >> > >>>> Based on your error messages, it's failing for mdio@0 which > >>>> corresponds to ext_mdio. But none of the board dts files in upstream > >>>> have a compatible property for "ext_mdio". Which means fw_devlink > >>>> _should_ propagate the gpio_intc IRQ dependency all the way up to > >>>> eth_phy. > >>>> > >>>> Also, in the failing case, can you run: > >>>> ls -ld supplier:* > >>>> > >>>> in the /sys/devices/..../ folder that corresponds to the > >>>> "eth_phy: mdio-multiplexer@4c000" DT node and tell me what it shows? > >>> > >>> Here you go: > >>> > >>> root@tiger-roach:~# find /sys/devices/ -name 'supplier*'|grep -i mdio | xargs ls -ld > >>> lrwxrwxrwx 1 root root 0 Aug 4 09:47 /sys/devices/platform/soc/ff600000.bus/ff64c000.mdio-multiplexer/supplier:platform:ff63c000.system-controller:clock-controller -> ../../../../virtual/devlink/platform:ff63c000.system-controller:clock-controller--platform:ff64c000.mdio-multiplexer > >> > >> As we discussed over chat, this was taken after the mdio-multiplexer > >> driver "successfully" probes this device. This will cause > >> SYNC_STATE_ONLY device links created by fw_devlink to be deleted > >> (because they are useless after a device probes). So, this doesn't > >> show the info I was hoping to demonstrate. > >> > >> In any case, one can see that fw_devlink properly created the device > >> link for the clocks dependency. So fw_devlink is parsing this node > >> properly. But it doesn't create a similar probe order enforcing device > >> link between the mdio-multiplexer and the gpio_intc because the > >> dependency is only present in a grand child DT node (ethernet-phy@0 > >> under ext_mdio). So fw_devlink is working as intended. > >> > >> I spent several hours squinting at the code/DT yesterday. Here's what > >> is going on and causing the problem: > >> > >> The failing driver in this case is > >> drivers/net/mdio/mdio-mux-meson-g12a.c. And the only DT node it's > >> handling is what I pasted above in this email. In the failure case, > >> the call flow is something like this: > >> > >> g12a_mdio_mux_probe() > >> -> mdio_mux_init() > >> -> of_mdiobus_register(ext_mdio DT node) > >> -> of_mdiobus_register_phy(ext_mdio DT node) > >> -> several calls deep fwnode_mdiobus_phy_device_register(ethernet_phy DT node) > >> -> Tried to get the IRQ listed in ethernet_phy and fails with > >> -EPROBE_DEFER because the IRQ driver isn't loaded yet. > >> > >> The error is propagated correctly all the way up to of_mdiobus_register(), but > >> mdio_mux_init() ignores the -EPROBE_DEFER from of_mdiobus_register() and just > >> continues on with the rest of the stuff and returns success as long as > >> one of the child nodes (in this case int_mdio) succeeds. > >> > >> Since the probe returns 0 without really succeeding, networking stuff > >> just fails badly after this. So, IMO, the real problem is with > >> mdio_mux_init() not propagating up the -EPROBE_DEFER. I gave Marc a > >> quick hack (pasted at the end of this email) to test my theory and he > >> confirmed that it fixes the issue (a few deferred probes later, things > >> work properly). > >> > >> Andrew, I don't see any good reason for mdio_mux_init() not > >> propagating the errors up correctly (at least for EPROBE_DEFER). I'll > >> send a patch to fix this. Please let me know if there's a reason it > >> has to stay as-is. > > > > I sent out the proper fix as a series: > > https://lore.kernel.org/lkml/20210804214333.927985-1-saravanak@google.com/T/#t > > Thanks a lot for digging here and providing the appropriate fixes ! You are welcome! Btw, 'm too lazy to download the mbox for your original patch (justifiably not cc'ed in it) and reply to it. I made this comment earlier too. Can you please use the IRQCHIP_PLATFORM_DRIVER_BEGIN and IRQCHIP_PLATFORM_DRIVER_END macros? They avoid boilerplate code every irqchip driver has to implement, adds some restrictions to avoid unbinding these drivers/unloading these modules, and also makes it easy to convert from IRQCHIP_DECLARE to a platform driver. It'll also allow you to drop the of_irq_find_parent() call in your probe. Cheers, Saravana > > Neil > > > > > Marc, can you give it a shot please? > > > > -Saravana > > > >> > >> -Saravana > >> > >> index 110e4ee85785..d973a267151f 100644 > >> --- a/drivers/net/mdio/mdio-mux.c > >> +++ b/drivers/net/mdio/mdio-mux.c > >> @@ -170,6 +170,9 @@ int mdio_mux_init(struct device *dev, > >> child_bus_node); > >> mdiobus_free(cb->mii_bus); > >> devm_kfree(dev, cb); > >> + /* Not a final fix. I think it can cause UAF issues. */ > >> + mdio_mux_uninit(pb); > >> + return r; > >> } else { > >> cb->next = pb->children; > >> pb->children = cb; > _______________________________________________ linux-amlogic mailing list linux-amlogic@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-amlogic