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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F251C433FE for ; Tue, 15 Feb 2022 15:20:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239034AbiBOPUc (ORCPT ); Tue, 15 Feb 2022 10:20:32 -0500 Received: from mxb-00190b01.gslb.pphosted.com ([23.128.96.19]:53402 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238746AbiBOPUa (ORCPT ); Tue, 15 Feb 2022 10:20:30 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ABF3A108BDC; Tue, 15 Feb 2022 07:20:19 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 633D3B81AE2; Tue, 15 Feb 2022 15:20:18 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id B299DC340ED; Tue, 15 Feb 2022 15:20:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1644938417; bh=cvvJ7Y1uOZsTSQ2EgEC3IyWSOPxIRWdyF+l3TLo73fA=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=BXhMIXjvG0BZrIJ4AGpwnd1+8ps21YN90C6Bx7kEUxLMo/3m80ucK5R2bJrFaSirP hI8uY5ws0E9o9oeS7ygCnZn6rdX20Z7ZkmnXG3d4Itv8GmCZs5x4WR3o9ZsiOD/0xK pjCS+7Sc/J+zkjtJHi1ejsXElZXX22ywEpgJgjn/E/G7RBWtv5lenBDo0E9BqIJC1b FoMjo02LYKKLmVYTRBDWVWEaSFKMJbpkAxHboipvvicoSmN7zmAnV/ynYX13emGxEm PaWa7Ira/bSgUfxTAwWlSxlmJ7QjNPXpVyokVltb4aiYv544BfK1XAdNmBeVpa6Doj 1g0Yi++3vwe1g== Date: Tue, 15 Feb 2022 09:20:14 -0600 From: Bjorn Helgaas To: Ben Dooks Cc: linux-kernel@vger.kernel.org, bhelgaas@google.comv, linux-pci@vger.kernel.org, paul.walmsley@sifive.com, greentime.hu@sifive.com, david.abdurachmanov@gmail.com, Rob Herring , Lorenzo Pieralisi Subject: Re: [PATCH 1/2] PCI: fu740: fix finding GPIOs Message-ID: <20220215152014.GA108566@bhelgaas> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Feb 15, 2022 at 11:21:03AM +0000, Ben Dooks wrote: > On 14/02/2022 16:05, Bjorn Helgaas wrote: > > [+cc Rob for possible DT/kernel match issue, > > Lorenzo (native host bridge driver maintainer)] > > > > s/fix finding/Fix finding/ (in subject) > > Or even better, say something specific about the DT properties in > > question, e.g., look for "reset" instead of "reset-gpios". > > > > On Mon, Feb 14, 2022 at 08:21:43AM +0000, Ben Dooks wrote: > > > The calls to devm_gpiod_get_optional() have the -gpios at the end of > > > the name. This means the pcie driver is not finding the necessary > > > reset or power GPOOs to allow the PCIe devices on the SiFive Unmatched > > > boards. > > > > "to allow the PCIe devices ...?" Something is missing from this > > sentence. "To allow the devices "? Or maybe the driver > > needs these GPIOs to power up the PCIe devices? > > > > I guess the implication is that the code looks for "reset-gpios" and > > "pwren-gpios", but the DT contains "reset" and "pwren"? > > > > But both Documentation/devicetree/bindings/pci/sifive,fu740-pcie.yaml > > and arch/riscv/boot/dts/sifive/fu740-c000.dtsi actually do contain > > "reset-gpios" and "pwren-gpios". > > Yes, the issue is the gpio core code adds either "-gpio" or "-gpios" > itself, thus the find code does not need this. The error messages and > DT are correct. I'll reword the initial paragraph to note that which > should also deal with the other comments: > > The calls to devm_gpiod_get_optional() have the -gpios at the end of > the name but the GPIO core code is already adding the suffix during > the lookup. This means the PCIe driver is not finding the necessary > reset or power lines to allow initialisation of the PCIe. Ah, that makes things make a LOT more sense! Please add something about "the '-gpios' suffix" for non-experts like me who don't know the inner workings of the GPIO core. The GPIO core seems slightly too helpful here -- we have to know about that detail to write error messages that make sense. > > If we *do* want to change the code, please change the error messages > > to match. > > See above, it is just devm_gpiod_get_optional() parameters at fault. > > > > This has not been a noted bug as the PCIe probe from u-boot has been > > > required to get the PCIe working due to other issues with the system > > > setup. It could have been broken since the driver inclusion, and not > > > been noticed as it is not necessary for the driver to funciton. > > > > Please add a line about what the connection between U-Boot and this > > issue is, e.g., maybe U-Boot powers up the devices, so we wouldn't > > notice the kernel's inability to do so? > > Does a reword to the following make better sense: > > This bug has not been noticed as if U-Boot has setup the GPIO lines > for the hardware when it does the PCIe initialisation (either by > booting from PCIe or user command to access PCIe) then the PCIe > will work in Linux. The U-Boot as supplied by SiFive does not by > default initialise any PCIe component. Sounds good, thanks. Bjorn