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=-11.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 5573AC11F66 for ; Tue, 29 Jun 2021 00:38:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3084161D07 for ; Tue, 29 Jun 2021 00:38:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232240AbhF2Ak6 (ORCPT ); Mon, 28 Jun 2021 20:40:58 -0400 Received: from mail.kernel.org ([198.145.29.99]:33794 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230086AbhF2Ak5 (ORCPT ); Mon, 28 Jun 2021 20:40:57 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 8DE9061CDC; Tue, 29 Jun 2021 00:38:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1624927110; bh=WZivHehj0fn2zKFGoJRQXv8BLeKMtv+80LunaiEbIWE=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=J1YEvvYJz8zqaFhsLjQqpLSF32fSg8EVWaPWDmNeDM59GEdo2i/8BDcz9EpIFVSCo 3yvEZc1PA3yJF+uTYog0vVSprT51/Q07l2wkuhnh3WaFGQoR1nHd980Jz+O7EYZPwq QeurrrGQPohqwS8DaCgRZT6R+g8O/slmEq4popLssCB3q/VGC9B1C6lQLyXIY1IayC 4MSXCiS2RRAV/kW4sr2eJXv+IycAui1dukFIBfTh9HbJ0WnlioejbQNfIU/iiwFZpD fnWoD7SLZ4z/gyfw3PH4wTebBOJmXO1q9gsWqNMBiI0FySzwSMpOv4+ZFr8ULcs65z S9ujiOiO3McFA== Date: Mon, 28 Jun 2021 19:38:29 -0500 From: Bjorn Helgaas To: Javier Martinez Canillas Cc: linux-kernel@vger.kernel.org, Peter Robinson , Shawn Lin , Bjorn Helgaas , Heiko Stuebner , Lorenzo Pieralisi , Rob Herring , linux-arm-kernel@lists.infradead.org, linux-pci@vger.kernel.org, linux-rockchip@lists.infradead.org, Michal Simek , Ley Foon Tan , rfi@lists.rocketboards.org, Jingoo Han , Thierry Reding , Jonathan Hunter , linux-tegra@vger.kernel.org Subject: Re: [PATCH v2] PCI: rockchip: Avoid accessing PCIe registers with clocks gated Message-ID: <20210629003829.GA3978248@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210624224040.GA3567297@bjorn-Precision-5520> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jun 24, 2021 at 05:40:40PM -0500, Bjorn Helgaas wrote: > [+cc Michal, Ley Foon, Jingoo, Thierry, Jonathan] > > On Tue, Jun 08, 2021 at 10:04:09AM +0200, Javier Martinez Canillas wrote: > > IRQ handlers that are registered for shared interrupts can be called at > > any time after have been registered using the request_irq() function. > > > > It's up to drivers to ensure that's always safe for these to be called. > > > > Both the "pcie-sys" and "pcie-client" interrupts are shared, but since > > their handlers are registered very early in the probe function, an error > > later can lead to these handlers being executed before all the required > > resources have been properly setup. > > > > For example, the rockchip_pcie_read() function used by these IRQ handlers > > expects that some PCIe clocks will already be enabled, otherwise trying > > to access the PCIe registers causes the read to hang and never return. > > > > The CONFIG_DEBUG_SHIRQ option tests if drivers are able to cope with their > > shared interrupt handlers being called, by generating a spurious interrupt > > just before a shared interrupt handler is unregistered. > > > > But this means that if the option is enabled, any error in the probe path > > of this driver could lead to one of the IRQ handlers to be executed. > > I'm not an IRQ expert, but I think this is an issue regardless of > CONFIG_DEBUG_SHIRQ, isn't it? Anything used by an IRQ handler should > be initialized before the handler is registered. CONFIG_DEBUG_SHIRQ > is just a way to help find latent problems. > > > In a rockpro64 board, the following sequence of events happens: > > > > 1) "pcie-sys" IRQ is requested and its handler registered. > > 2) "pcie-client" IRQ is requested and its handler registered. > > 3) probe later fails due readl_poll_timeout() returning a timeout. > > 4) the "pcie-sys" IRQ is unregistered. > > 5) CONFIG_DEBUG_SHIRQ triggers a spurious interrupt. > > 6) "pcie-client" IRQ handler is called for this spurious interrupt. > > 7) IRQ handler tries to read PCIE_CLIENT_INT_STATUS with clocks gated. > > 8) the machine hangs because rockchip_pcie_read() call never returns. > > > > To avoid cases like this, the handlers don't have to be registered until > > very late in the probe function, once all the resources have been setup. > > > > So let's just move all the IRQ init before the pci_host_probe() call, that > > will prevent issues like this and seems to be the correct thing to do too. > > Previously we registered rockchip_pcie_subsys_irq_handler() and > rockchip_pcie_client_irq_handler() before the PCIe clocks were > enabled. That's a problem because they depend on those clocks being > enabled, and your patch fixes that. > > rockchip_pcie_legacy_int_handler() depends on rockchip->irq_domain, > which isn't initialized until rockchip_pcie_init_irq_domain(). > Previously we registered rockchip_pcie_legacy_int_handler() as the > handler for the "legacy" IRQ before rockchip_pcie_init_irq_domain(). > > I think your patch *also* fixes that problem, right? The lack of consistency in how we use irq_set_chained_handler_and_data() really bugs me. Your patch fixes the ordering issue where we installed rockchip_pcie_legacy_int_handler() before initializing data (rockchip->irq_domain) that it depends on. But AFAICT, rockchip still has the problem that we don't *unregister* rockchip_pcie_legacy_int_handler() when the rockchip-pcie module is removed. Doesn't this mean that if we unload the module, then receive an interrupt from the device, we'll try to call a function that is no longer present? > > diff --git a/drivers/pci/controller/pcie-rockchip-host.c b/drivers/pci/controller/pcie-rockchip-host.c > > index f1d08a1b159..78d04ac29cd 100644 > > --- a/drivers/pci/controller/pcie-rockchip-host.c > > +++ b/drivers/pci/controller/pcie-rockchip-host.c > > @@ -592,10 +592,6 @@ static int rockchip_pcie_parse_host_dt(struct rockchip_pcie *rockchip) > > if (err) > > return err; > > > > - err = rockchip_pcie_setup_irq(rockchip); > > - if (err) > > - return err; > > - > > rockchip->vpcie12v = devm_regulator_get_optional(dev, "vpcie12v"); > > if (IS_ERR(rockchip->vpcie12v)) { > > if (PTR_ERR(rockchip->vpcie12v) != -ENODEV) > > @@ -973,8 +969,6 @@ static int rockchip_pcie_probe(struct platform_device *pdev) > > if (err) > > goto err_vpcie; > > > > - rockchip_pcie_enable_interrupts(rockchip); > > - > > err = rockchip_pcie_init_irq_domain(rockchip); > > if (err < 0) > > goto err_deinit_port; > > @@ -992,6 +986,12 @@ static int rockchip_pcie_probe(struct platform_device *pdev) > > bridge->sysdata = rockchip; > > bridge->ops = &rockchip_pcie_ops; > > > > + err = rockchip_pcie_setup_irq(rockchip); > > + if (err) > > + goto err_remove_irq_domain; > > + > > + rockchip_pcie_enable_interrupts(rockchip); > > + > > err = pci_host_probe(bridge); > > if (err < 0) > > goto err_remove_irq_domain; > > -- > > 2.31.1 > >