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PCI: Workaround missing pci_set_master in pci drivers

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Ben Herrenschmidt found that commit 928bea964827 ("PCI: Delay enabling
bridges until they're needed") breaks PCI in some powerpc environments.

The reason is that the PCIe port driver will call pci_enable_device() on
the bridge, so the device is enabled, but skips pci_set_master because
pcie_port_auto and no acpi on powerpc.

Because of that, pci_enable_bridge() later on (called as a result of the
child device driver doing pci_enable_device) will see the bridge as
already enabled and will not call pci_set_master() on it.

Fixed by add checking in pci_enable_bridge, and call pci_set_master
if driver skip that.

That will make the code more robot and wade off problem for missing
pci_set_master in drivers.

Reported-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Yinghai Lu 2013-11-05 13:34:38 -07:00 committed by Bjorn Helgaas
parent 6b87e700cd
commit cf3e1feba7
1 changed files with 7 additions and 1 deletions
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8
drivers/pci/pci.c
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@ -1155,8 +1155,14 @@ static void pci_enable_bridge(struct pci_dev *dev)
pci_enable_bridge(dev->bus->self);
if (pci_is_enabled(dev))
if (pci_is_enabled(dev)) {
if (!dev->is_busmaster) {
dev_warn(&dev->dev, "driver skip pci_set_master, fix it!\n");
pci_set_master(dev);
}
return;
}
retval = pci_enable_device(dev);
if (retval)
dev_err(&dev->dev, "Error enabling bridge (%d), continuing\n",