On Thu, Aug 23, 2012 at 12:28:23AM -0700, Olof Johansson wrote: > Hi, > > On Mon, Jul 9, 2012 at 11:20 AM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote: > > After 253d2e5498, we disable MEM and IO decoding for most devices while we > > size 32-bit BARs. However, we restore the original COMMAND register before > > we size the upper 32 bits of 64-bit BARs, so we can still cause a conflict. > > > > This patch waits to restore the original COMMAND register until we're > > completely finished sizing the BAR. > > > > Reference: https://lkml.org/lkml/2007/8/25/154 > > Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> > > This patch causes boot lockup on PA Semi hardware, since it disables > the bar on the UART that is used for console, and it has printks > between the old and the new re-enable location. If I boot with 'debug' > level for printk, I hit this. If I boot with just regular console > args, I don't. > > I'm guessing any other platform that uses MMIO-based UART on PCI for > console will have similar issues. I can verify on Chrome OS x86 > hardware tomorrow if legacy powerpc isn't important enough to care > about. :-) > > I have no proposal for a fix for this. Can you please consider > reverting for 3.6 unless someone has a better idea? Thanks a lot for finding and debugging this! Can you try the patch below? commit cfc29ece86d648e63fb46de81b2bf8e3e107672c Author: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> Date: Thu Aug 23 10:53:08 2012 -0600 PCI: Don't print anything while decoding is disabled If we try to print to the console device while its decoding is disabled, the system will hang. Reported-by: Olof Johansson <olof@xxxxxxxxx> Signed-off-by: Bjorn Helgaas <bhelgaas@xxxxxxxxxx> diff --git a/drivers/pci/probe.c b/drivers/pci/probe.c index 6c143b4..9f8a6b7 100644 --- a/drivers/pci/probe.c +++ b/drivers/pci/probe.c @@ -144,15 +144,13 @@ static inline unsigned long decode_bar(struct pci_dev *dev, u32 bar) case PCI_BASE_ADDRESS_MEM_TYPE_32: break; case PCI_BASE_ADDRESS_MEM_TYPE_1M: - dev_info(&dev->dev, "1M mem BAR treated as 32-bit BAR\n"); + /* 1M mem BAR treated as 32-bit BAR */ break; case PCI_BASE_ADDRESS_MEM_TYPE_64: flags |= IORESOURCE_MEM_64; break; default: - dev_warn(&dev->dev, - "mem unknown type %x treated as 32-bit BAR\n", - mem_type); + /* mem unknown type treated as 32-bit BAR */ break; } return flags; @@ -173,9 +171,11 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type, u32 l, sz, mask; u16 orig_cmd; struct pci_bus_region region; + bool bar_too_big = false, bar_disabled = false; mask = type ? PCI_ROM_ADDRESS_MASK : ~0; + /* No printks while decoding is disabled! */ if (!dev->mmio_always_on) { pci_read_config_word(dev, PCI_COMMAND, &orig_cmd); pci_write_config_word(dev, PCI_COMMAND, @@ -240,8 +240,7 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type, goto fail; if ((sizeof(resource_size_t) < 8) && (sz64 > 0x100000000ULL)) { - dev_err(&dev->dev, "reg %x: can't handle 64-bit BAR\n", - pos); + bar_too_big = true; goto fail; } @@ -252,12 +251,11 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type, region.start = 0; region.end = sz64; pcibios_bus_to_resource(dev, res, ®ion); + bar_disabled = true; } else { region.start = l64; region.end = l64 + sz64; pcibios_bus_to_resource(dev, res, ®ion); - dev_printk(KERN_DEBUG, &dev->dev, "reg %x: %pR\n", - pos, res); } } else { sz = pci_size(l, sz, mask); @@ -268,18 +266,23 @@ int __pci_read_base(struct pci_dev *dev, enum pci_bar_type type, region.start = l; region.end = l + sz; pcibios_bus_to_resource(dev, res, ®ion); - - dev_printk(KERN_DEBUG, &dev->dev, "reg %x: %pR\n", pos, res); } - out: + goto out; + + +fail: + res->flags = 0; +out: if (!dev->mmio_always_on) pci_write_config_word(dev, PCI_COMMAND, orig_cmd); + if (bar_too_big) + dev_err(&dev->dev, "reg %x: can't handle 64-bit BAR\n", pos); + if (res->flags && !bar_disabled) + dev_printk(KERN_DEBUG, &dev->dev, "reg %x: %pR\n", pos, res); + return (res->flags & IORESOURCE_MEM_64) ? 1 : 0; - fail: - res->flags = 0; - goto out; } static void pci_read_bases(struct pci_dev *dev, unsigned int howmany, int rom) -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
