Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Wed, 20 Jul 2022 17:08:40 -0500
From:   Bjorn Helgaas <helgaas@kernel.org>
To:     Jim Quinlan <jim2101024@gmail.com>
Cc:     linux-pci@vger.kernel.org,
        Nicolas Saenz Julienne <nsaenz@kernel.org>,
        Bjorn Helgaas <bhelgaas@google.com>,
        Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>,
        Cyril Brulebois <kibi@debian.org>,
        bcm-kernel-feedback-list@broadcom.com, james.quinlan@broadcom.com,
        Florian Fainelli <f.fainelli@gmail.com>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        Rob Herring <robh@kernel.org>,
        Krzysztof =?utf-8?Q?Wilczy=C5=84ski?= <kw@linux.com>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-rpi-kernel@lists.infradead.org>,
        "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" 
        <linux-arm-kernel@lists.infradead.org>,
        open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v2 3/6] PCI: brcmstb: Add "refusal mode" to preclude
 PCIe-induced CPU aborts
Message-ID: <20220720220840.GA1663326@bhelgaas>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20220716222454.29914-4-jim2101024@gmail.com>
Precedence: bulk

On Sat, Jul 16, 2022 at 06:24:50PM -0400, Jim Quinlan wrote:
> Our PCIe RC HW has an atypical behavior: if it does not have PCIe link
> established between itself and downstream, any subsequent config space
> access causes a CPU abort.  This commit sets a "refusal mode" if the PCIe
> link-up fails, and this has our pci_ops map_bus function returning a NULL
> address, which in turn precludes the access from happening.

> @@ -687,6 +688,19 @@ static void __iomem *brcm_pcie_map_conf(struct pci_bus *bus, unsigned int devfn,

Oh, and I forgot to mention that brcmstb is one of the few drivers
that doesn't name these functions ".*_map_bus()".  It's helpful when
they all match a simple grep pattern.  Maybe a patch at the end could
fix this.