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Date:   Mon, 24 Sep 2018 16:52:18 +0200
From:   Thomas Petazzoni <thomas.petazzoni@bootlin.com>
To:     Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc:     Russell King - ARM Linux <linux@armlinux.org.uk>,
        Jan Kundr??t <jan.kundrat@cesnet.cz>,
        Baruch Siach <baruch@tkos.co.il>,
        Jason Cooper <jason@lakedaemon.net>, linux-pci@vger.kernel.org,
        linux-kernel@vger.kernel.org, Bjorn Helgaas <bhelgaas@google.com>,
        linux-arm-kernel@lists.infradead.org
Subject: Re: [BISECTED] Regression: Solidrun Clearfog Base won't boot since
 "PCI: mvebu: Only remap I/O space if configured"
Message-ID: <20180924165218.26c7c418@windsurf>
In-Reply-To: <20180924141512.GA11875@e107981-ln.cambridge.arm.com>
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        <20180913094515.351967bb@windsurf>
        <5ad46fec-a71a-477a-b23f-d20aacfb481d@cesnet.cz>
        <20180913104241.65db8243@windsurf>
        <20180924101213.GO30658@n2100.armlinux.org.uk>
        <20180924122614.70738b5c@windsurf>
        <20180924111341.GP30658@n2100.armlinux.org.uk>
        <20180924141203.3df9707a@windsurf>
        <20180924124620.GA10322@e107981-ln.cambridge.arm.com>
        <20180924151040.5e57462b@windsurf>
        <20180924141512.GA11875@e107981-ln.cambridge.arm.com>
Organization: Bootlin (formerly Free Electrons)
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Hello,

On Mon, 24 Sep 2018 15:15:12 +0100, Lorenzo Pieralisi wrote:

> I understand that, I wanted to make sure we come up with a fix asap
> and what I put forward would cover everything discussed in this thread,
> at least temporarily, giving us time to check ISA related issues while
> unmapping IO space.

Something like this should implemented what you suggest I guess:

diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
index 50eb0729385b..a41d79b8d46a 100644
--- a/drivers/pci/controller/pci-mvebu.c
+++ b/drivers/pci/controller/pci-mvebu.c
@@ -1145,7 +1145,6 @@ static int mvebu_pcie_parse_request_resources(struct mvebu_pcie *pcie)
 {
        struct device *dev = &pcie->pdev->dev;
        struct device_node *np = dev->of_node;
-       unsigned int i;
        int ret;
 
        INIT_LIST_HEAD(&pcie->resources);
@@ -1179,13 +1178,58 @@ static int mvebu_pcie_parse_request_resources(struct mvebu_pcie *pcie)
                                         resource_size(&pcie->io) - 1);
                pcie->realio.name = "PCI I/O";
 
+               pci_add_resource(&pcie->resources, &pcie->realio);
+       }
+
+       return devm_request_pci_bus_resources(dev, &pcie->resources);
+}
+
+/*
+ * This is a copy of pci_host_probe(), except that it does the I/O
+ * remap as the last step, once we are sure we won't fail.
+ *
+ * It should be removed once the I/O remap error handling issue has
+ * been sorted out.
+ */
+static int mvebu_pci_host_probe(struct pci_host_bridge *bridge)
+{
+       struct mvebu_pcie *pcie;
+       struct pci_bus *bus, *child;
+       int ret;
+
+       ret = pci_scan_root_bus_bridge(bridge);
+       if (ret < 0) {
+               dev_err(bridge->dev.parent, "Scanning root bridge failed");
+               return ret;
+       }
+
+       pcie = pci_host_bridge_priv(bridge);
+       if (resource_size(&pcie->io) != 0) {
+               unsigned int i;
+
                for (i = 0; i < resource_size(&pcie->realio); i += SZ_64K)
                        pci_ioremap_io(i, pcie->io.start + i);
+       }
 
-               pci_add_resource(&pcie->resources, &pcie->realio);
+       bus = bridge->bus;
+
+       /*
+        * We insert PCI resources into the iomem_resource and
+        * ioport_resource trees in either pci_bus_claim_resources()
+        * or pci_bus_assign_resources().
+        */
+       if (pci_has_flag(PCI_PROBE_ONLY)) {
+               pci_bus_claim_resources(bus);
+       } else {
+               pci_bus_size_bridges(bus);
+               pci_bus_assign_resources(bus);
+
+               list_for_each_entry(child, &bus->children, node)
+                       pcie_bus_configure_settings(child);
        }
 
-       return devm_request_pci_bus_resources(dev, &pcie->resources);
+       pci_bus_add_devices(bus);
+       return 0;
 }
 
 static int mvebu_pcie_probe(struct platform_device *pdev)
@@ -1268,7 +1312,7 @@ static int mvebu_pcie_probe(struct platform_device *pdev)
        bridge->align_resource = mvebu_pcie_align_resource;
        bridge->msi = pcie->msi;
 
-       return pci_host_probe(bridge);
+       return mvebu_pci_host_probe(bridge);
 }
 
 static const struct of_device_id mvebu_pcie_of_match_table[] = {

If that's what you meant, I'll go ahead and test on actual hardware and
submit as a proper patch.

Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com