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 <bhelg...@google.com> 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 <bhelg...@google.com>
>
> 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 <bhelg...@google.com>
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 <o...@lixom.net>
Signed-off-by: Bjorn Helgaas <bhelg...@google.com>
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)
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