On 30/10/12 03:13, Bjorn Helgaas wrote:
On Mon, Oct 29, 2012 at 8:40 AM, Ian Abbott <abbotti@xxxxxxxxx> wrote:The PLX PCI 9050 PCI Target bridge controller has a bug that prevents its local configuration registers being read through BAR0 (memory) or BAR1 (i/o) if the base address lies on an odd 128-byte boundary, i.e. if bit 7 of the base address is non-zero. This bug is described in the PCI 9050 errata list, version 1.4, May 2005. It was fixed in the pin-compatible PCI 9052, which can be distinguished from the PCI 9050 by checking the revision in the PCI header, which is hard-coded for these chips. Workaround the problem by re-allocating the affected regions to a 256-byte boundary. Note that BAR0 and/or BAR1 may have been disabled (size 0) during initialization of the PCI chip when its configuration is read from a serial EEPROM. Currently, the fix-up has only been used for devices with the default vendor and device ID of the PLX PCI 9050. The PCI 9052 shares the same default device ID as the PCI 9050 but they have different PCI revision codes. Signed-off-by: Ian Abbott <abbotti@xxxxxxxxx> --- drivers/pci/quirks.c | 25 +++++++++++++++++++++++++ 1 file changed, 25 insertions(+) diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index 7a451ff..7e6be56 100644 --- a/drivers/pci/quirks.c +++ b/drivers/pci/quirks.c @@ -1790,6 +1790,31 @@ DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_TOSHIBA_2, PCI_DEVICE_ID_TOSHIBA_TC86C001_IDE, quirk_tc86c001_ide); +/* + * PLX PCI 9050 PCI Target bridge controller has an errata that prevents the + * local configuration registers accessible via BAR0 (memory) or BAR1 (i/o) + * being read correctly if bit 7 of the base address is set. + * The BAR0 or BAR1 region may be disabled (size 0) or enabled (size 128). + * Re-allocate the regions to a 256-byte boundary if necessary. + */ +static void __devinit quirk_plx_pci9050(struct pci_dev *dev) +{ + unsigned int bar; + + /* Fixed in revision 2 (PCI 9052). */ + if (dev->revision >= 2) + return; + for (bar = 0; bar <= 1; bar++) + if (pci_resource_len(dev, bar) == 0x80 && + (pci_resource_start(dev, bar) & 0x80)) { + struct resource *r = &dev->resource[bar]; + r->start = 0; + r->end = 0xff;I assume the intent here is to make these BARs "unassigned" so they will be reassigned later? We don't yet have a clean generic way of indicating "unassigned," so "r->start = 0" is the best we can do for now.
I more-or-less copied the method from quirk_tc86c001_ide(). I don't have any prior experience with writing PCI quirks, so I don't know if this is the best way to do it! All I really care about is that these BARs don't have bit 7 set.
I think it'd be nice to have a dev_info() here to explain what's going on. Otherwise, the dmesg will be a bit mysterious.
OK, I'll add that in the next version of this patch. -- -=( Ian Abbott @ MEV Ltd. E-mail: <abbotti@xxxxxxxxx> )=- -=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=- -- 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
