Messages in this thread Patch in this message | | | Date | Mon, 24 Sep 2018 15:10:40 +0200 | From | Thomas Petazzoni <> | Subject | Re: [BISECTED] Regression: Solidrun Clearfog Base won't boot since "PCI: mvebu: Only remap I/O space if configured" |
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Hello,
On Mon, 24 Sep 2018 13:46:29 +0100, Lorenzo Pieralisi wrote:
> What I think you can do short term, given that AFAICS MVEBU is not > removable, instead of using pci_host_probe() you move part of its code > into the driver and make sure that you remap IO as last operation before > probe completion (ie after scanning the host bridge) so that you do not > need to unmap it on failure; write a commit log summarising/linking this > thread please and when v4.20 lands we will give this a more thorough > look as Russell requested. > > How does that sound ?
The only thing that can fail in pci_host_probe() is:
ret = pci_scan_root_bus_bridge(bridge); if (ret < 0) { dev_err(bridge->dev.parent, "Scanning root bridge failed"); return ret; }
In the pci-mvebu driver prior to the conversion to pci_host_probe(), the code flow at the end of ->probe() was:
mvebu_pcie_enable() pci_common_init_dev() pcibios_init_hw()
and pcibios_init_hw() calls pci_scan_root_bus_bridge(), without doing much about the return value other than issuing a warning:
ret = pci_scan_root_bus_bridge(bridge); }
if (WARN(ret < 0, "PCI: unable to scan bus!")) { pci_free_host_bridge(bridge); break; }
I.e, even before the conversion to pci_host_probe(), in case of failure in pci_scan_root_bus_bridge(), we would have the I/O mapping in place, but the PCI controller not registered.
We could keep the same (not great) behavior by doing:
diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c index 50eb0729385b..487492f0c5f7 100644 --- a/drivers/pci/controller/pci-mvebu.c +++ b/drivers/pci/controller/pci-mvebu.c @@ -1179,9 +1179,6 @@ static int mvebu_pcie_parse_request_resources(struct mvebu_pcie *pcie) resource_size(&pcie->io) - 1); pcie->realio.name = "PCI I/O"; - 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); } @@ -1197,7 +1194,7 @@ static int mvebu_pcie_probe(struct platform_device *pdev) struct device_node *child; int num, i, ret; - bridge = devm_pci_alloc_host_bridge(dev, sizeof(struct mvebu_pcie)); + bridge = pci_alloc_host_bridge(sizeof(struct mvebu_pcie)); if (!bridge) return -ENOMEM; @@ -1212,8 +1209,10 @@ static int mvebu_pcie_probe(struct platform_device *pdev) num = of_get_available_child_count(np); pcie->ports = devm_kcalloc(dev, num, sizeof(*pcie->ports), GFP_KERNEL); - if (!pcie->ports) - return -ENOMEM; + if (!pcie->ports) { + ret = -ENOMEM; + goto free_host_bridge; + } i = 0; for_each_available_child_of_node(np, child) { @@ -1222,7 +1221,7 @@ static int mvebu_pcie_probe(struct platform_device *pdev) ret = mvebu_pcie_parse_port(pcie, port, child); if (ret < 0) { of_node_put(child); - return ret; + goto free_host_bridge; } else if (ret == 0) { continue; } @@ -1268,7 +1267,21 @@ 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); + if (resource_size(&pcie->io) != 0) { + for (i = 0; i < resource_size(&pcie->realio); i += SZ_64K) + pci_ioremap_io(i, pcie->io.start + i); + } + + ret = pci_host_probe(bridge); + if (ret) + pci_free_host_bridge(bridge); + + /* Yes, when pci_host_probe() returns a failure, we don't care */ + return 0; + +free_host_bridge: + pci_free_host_bridge(bridge); + return ret; } static const struct of_device_id mvebu_pcie_of_match_table[] = { I.e, we simply ignore the failure of pci_host_probe().
To be honest, I really prefer the option of introducing pci_unmap_io().
Best regards,
Thomas -- Thomas Petazzoni, CTO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
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