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Tue, 18 Aug 2020 18:34:38 +0100 MIME-Version: 1.0 Date: Tue, 18 Aug 2020 18:34:38 +0100 From: Marc Zyngier To: Rob Herring Subject: Re: [PATCH 1/2] PCI: rockchip: Work around missing device_type property in DT In-Reply-To: References: <20200815125112.462652-2-maz@kernel.org> <20200815232228.GA1325245@bjorn-Precision-5520> <87pn7qnabq.wl-maz@kernel.org> User-Agent: Roundcube Webmail/1.4.7 Message-ID: <72c10e43023289b9a4c36226fe3fd5d9@kernel.org> X-Sender: maz@kernel.org X-SA-Exim-Connect-IP: 51.254.78.96 X-SA-Exim-Rcpt-To: robh@kernel.org, helgaas@kernel.org, linux-pci@vger.kernel.org, linux-rockchip@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, lorenzo.pieralisi@arm.com, heiko@sntech.de, shawn.lin@rock-chips.com, bhelgaas@google.com, kernel-team@android.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200818_133440_999329_2010909F X-CRM114-Status: GOOD ( 40.73 ) 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: Lorenzo Pieralisi , Heiko Stuebner , PCI , Shawn Lin , linux-kernel@vger.kernel.org, "open list:ARM/Rockchip SoC..." , Bjorn Helgaas , Bjorn Helgaas , Android Kernel Team , "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" 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 2020-08-18 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")); } static void of_bus_pci_count_cells(struct device_node *np, It should address all the drivers in one go, and yet tell users that something is amiss. M. -- Jazz is not dead. It just smells funny... _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel