From: Yinghai Lu Date: Sat, 28 Sep 2013 20:13:07 +0000 (-0700) Subject: PCI: Workaround missing pci_set_master in pci drivers X-Git-Tag: firefly_0821_release~176^2~5236 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=f41f064cf4352e6a7fd982f1de8a690897702513;p=firefly-linux-kernel-4.4.55.git PCI: Workaround missing pci_set_master in pci drivers 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 Signed-off-by: Yinghai Lu Signed-off-by: Linus Torvalds --- diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index e8ccf6c0f08a..bdd64b1b4817 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -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",