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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=OMrT9C5AFoMvfd0icRmwdmikCEIc/NXJSQt8b1yXCkw=; b=auEgKZILkFD00pTIwH9941IG5bamHSBLSjMfe5xTCahTQ3WvPAEPKvcngCySvYB3UP LaRtyg9cEIkvvEU9MGtJmluixoZIlIRkSoG7k/zNL8jLF7DqCj3SvK0uhr8TraRu8jER kDihIp0kD4mCOYuBvpmTTFkDTLSAVYuNJ+R4a8KAGGMFeayKZ5SDOrPN6abnCxZmF2yk 7xmzWTKnbC837aQrg55GCp5Hl8fh2pbz1xXSpdDP7KUtrnBUYwNCjfSpAXkWFj437bbE 7yCLky44I2nMhEoSQ9sdnAZGRuEh3c60y1YjEYoT/HELfOA4CLZTuAbGpsirEDEwYeii ObGw== X-Gm-Message-State: AOAM533T7Z00Vt2OVvmRBOp+QpAQiTDBHtVrFFfTVVFP601QbsXWCnB3 f+ncrKBXlXzWUK4S3RavEirw7OA+y01FROnAETsADQ== X-Google-Smtp-Source: ABdhPJzVVyPcZ+7Gs0AXJVZxiCetyUr6nk23IoYNH1FZlus2gp2HDkcMI/FTOQ/mx9fK0t2ODFmqRjeqa113FBmxApY= X-Received: by 2002:a17:90a:f98e:: with SMTP id cq14mr871303pjb.51.1597772970220; Tue, 18 Aug 2020 10:49:30 -0700 (PDT) MIME-Version: 1.0 References: <20200815125112.462652-2-maz@kernel.org> <20200815232228.GA1325245@bjorn-Precision-5520> <87pn7qnabq.wl-maz@kernel.org> <72c10e43023289b9a4c36226fe3fd5d9@kernel.org> In-Reply-To: <72c10e43023289b9a4c36226fe3fd5d9@kernel.org> From: Saravana Kannan Date: Tue, 18 Aug 2020 10:48:54 -0700 Message-ID: Subject: Re: [PATCH 1/2] PCI: rockchip: Work around missing device_type property in DT To: Marc Zyngier X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200818_134934_847593_B2970591 X-CRM114-Status: GOOD ( 44.09 ) 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: Rob Herring , Lorenzo Pieralisi , Heiko Stuebner , PCI , Shawn Lin , LKML , "open list:ARM/Rockchip SoC..." , Bjorn Helgaas , Bjorn Helgaas , Android Kernel Team , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Tue, Aug 18, 2020 at 10:34 AM Marc Zyngier wrote: > > On 2020-08-18 15:23, Rob Herring wrote: > > On Tue, Aug 18, 2020 at 1:35 AM Marc Zyngier wrote: > >> > >> On 2020-08-17 17:12, Rob Herring wrote: > >> > On Sun, Aug 16, 2020 at 4:40 AM Marc Zyngier wrote: > >> >> > >> >> On Sun, 16 Aug 2020 00:22:28 +0100, > >> >> Bjorn Helgaas wrote: > >> >> > > >> >> > On Sat, Aug 15, 2020 at 01:51:11PM +0100, Marc Zyngier wrote: > >> >> > > Recent changes to the DT PCI bus parsing made it mandatory for > >> >> > > device tree nodes describing a PCI controller to have the > >> >> > > 'device_type = "pci"' property for the node to be matched. > >> >> > > > >> >> > > Although this follows the letter of the specification, it > >> >> > > breaks existing device-trees that have been working fine > >> >> > > for years. Rockchip rk3399-based systems are a prime example > >> >> > > of such collateral damage, and have stopped discovering their > >> >> > > PCI bus. > >> >> > > > >> >> > > In order to paper over the blunder, let's add a workaround > >> >> > > to the pcie-rockchip driver, adding the missing property when > >> >> > > none is found at boot time. A warning will hopefully nudge the > >> >> > > user into updating their DT to a fixed version if they can, but > >> >> > > the insentive is obviously pretty small. > >> >> > > >> >> > s/insentive/incentive/ (Lorenzo or I can fix this up) > >> >> > > >> >> > > Fixes: 2f96593ecc37 ("of_address: Add bus type match for pci ranges parser") > >> >> > > Suggested-by: Roh Herring > >> >> > > >> >> > s/Roh/Rob/ (similarly) > >> >> > >> >> Clearly not my day when it comes to proofreading commit messages. > >> >> Thanks for pointing this out, and in advance for fixing it up. > >> >> > >> >> > > >> >> > > Signed-off-by: Marc Zyngier > >> >> > > >> >> > This looks like a candidate for v5.9, since 2f96593ecc37 was merged > >> >> > during the v5.9 merge window, right? > >> >> > >> >> Absolutely. > >> >> > >> >> > I wonder how many other DTs are similarly broken? Maybe Rob's DT > >> >> > checker has already looked? > >> >> > >> >> I've just managed to run the checker, which comes up with all kinds of > >> >> goodies. Apart from the above, it also spots the following: > >> >> > >> >> - arch/arm64/boot/dts/mediatek/mt7622.dtsi: Has a device_type property > >> >> in its main PCIe node, but not in the child nodes. It isn't obvious > >> >> to me whether that's a violation or not (the spec doesn't say > >> >> whether the property should be set on a per-port basis). Rob? > >> > > >> > The rule is bridge nodes should have 'device_type = "pci"'. But what's > >> > needed to fix these cases is setting device_type where we are parsing > >> > ranges or dma-ranges which we're not doing on the child ndes. > >> > Otherwise, I don't think it matters in this case unless you have child > >> > (grandchild here) nodes for PCI devices. If you did have child nodes, > >> > the address translation was already broken before this change. > >> > >> Fair enough. > >> > >> >> - arch/arm64/boot/dts/qcom/msm8996.dtsi: Only one out of the three > >> >> PCIe nodes has the device_type property, probably broken similarly > >> >> to rk3399. > >> > > >> > The only upstream board is DB820c, so probably not as wide an impact... > >> > > >> > There are also 92 (lots of duplicates due to multiple boards) more > >> > cases in arch/arm/. A log is here[1]. > >> > >> Mostly Broadcom stuff, apparently. I'll see if I can have a stab > >> at it (although someone will have to test it). > >> > >> > > >> >> I could move the workaround to drivers/pci/of.c, and have it called > >> >> from the individual drivers. I don't have the HW to test those though. > >> >> > >> >> Thoughts? > >> > > >> > I think we should go with my other suggestion of looking at the node > >> > name. Looks like just checking 'pcie' is enough. We can skip 'pci' as > >> > I don't see any cases. > >> > >> I really dislike it. > >> > >> Once we put this node name matching in, there is no incentive for > >> people to write their DT correctly at all. It also sound pretty > >> fragile (what if the PCIe node is named something else?). > > > > That would require 2 wrongs. Both missing device_type and wrong node > > name. You could still warn if we matched on node name. > > OK. So how about something like this? > > diff --git a/drivers/of/address.c b/drivers/of/address.c > index 590493e04b01..a7a6ee599b14 100644 > --- a/drivers/of/address.c > +++ b/drivers/of/address.c > @@ -134,9 +134,13 @@ static int of_bus_pci_match(struct device_node *np) > * "pciex" is PCI Express > * "vci" is for the /chaos bridge on 1st-gen PCI powermacs > * "ht" is hypertransport > + * > + * If none of the device_type match, and that the node name is > + * "pcie", accept the device as PCI (with a warning). > */ > return of_node_is_type(np, "pci") || of_node_is_type(np, "pciex") || > - of_node_is_type(np, "vci") || of_node_is_type(np, "ht"); > + of_node_is_type(np, "vci") || of_node_is_type(np, "ht") || > + WARN_ON_ONCE(of_node_name_eq(np, "pcie")); I don't think we need the _ONCE. Otherwise, it'd warn only for the first device that has this problem. How about? WARN(of_node_name_eq(np, "pcie"), "Missing device type in %pOF", np) That'll even tell them which node is bad. -Saravana _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel