Hi,
The TI XIO2000A/XIO2200A PCIe-PCI bridge (VID: 104C, DID: 8231)
erroneously handles fast back-to-back transfers on its subordinate bus
segment. The behavior is seen when there are multiple devices
downstream and transfers from both devices result in a fast b2b
transfer. This confuses the PCIe-PCI bridge and results in data
corruption.
One way to work around the buggy bridge would be to disable fast b2b
transfers on any device on the subordinate bus-segment by writing the
appropriate bits in the device's pci-configspace command register.
Are there any suggestions on how this might be handled? Should this
be addressed in the kernel?
Thanks,
Gabe Black
On Tue, 22 Sep 2009 14:01:06 -0500
Gabe Black <[email protected]> wrote:
> Hi,
>
> The TI XIO2000A/XIO2200A PCIe-PCI bridge (VID: 104C, DID: 8231)
> erroneously handles fast back-to-back transfers on its subordinate bus
> segment. The behavior is seen when there are multiple devices
> downstream and transfers from both devices result in a fast b2b
> transfer. This confuses the PCIe-PCI bridge and results in data
> corruption.
>
> One way to work around the buggy bridge would be to disable fast b2b
> transfers on any device on the subordinate bus-segment by writing the
> appropriate bits in the device's pci-configspace command register.
>
> Are there any suggestions on how this might be handled? Should this
> be addressed in the kernel?
sounds like this is worth a PCI quirk in the kernel...
--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
On Tue, Sep 22, 2009 at 2:11 PM, Arjan van de Ven <[email protected]> wrote:
>
> sounds like this is worth a PCI quirk in the kernel...
>
Is there documentation on how one would go about writing a "PCI quirk"?
Thanks,
Gabe
On Tue, 22 Sep 2009 14:37:16 -0500
Gabe Black <[email protected]> wrote:
> On Tue, Sep 22, 2009 at 2:11 PM, Arjan van de Ven
> <[email protected]> wrote:
> >
> > sounds like this is worth a PCI quirk in the kernel...
> >
>
> Is there documentation on how one would go about writing a "PCI
> quirk"?
>
I would look at the existing quirks in the drivers/pci/quirks.c file...
plenty of good (or bad, depending on how you look at it) examples...
--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
On Tue, 22 Sep 2009 22:07:47 +0200
Arjan van de Ven <[email protected]> wrote:
> On Tue, 22 Sep 2009 14:37:16 -0500
> Gabe Black <[email protected]> wrote:
>
> > On Tue, Sep 22, 2009 at 2:11 PM, Arjan van de Ven
> > <[email protected]> wrote:
> > >
> > > sounds like this is worth a PCI quirk in the kernel...
> > >
> >
> > Is there documentation on how one would go about writing a "PCI
> > quirk"?
> >
>
> I would look at the existing quirks in the drivers/pci/quirks.c
> file... plenty of good (or bad, depending on how you look at it)
> examples...
Gabe, did you figure out how to do this? Do you need any more help?
--
Jesse Barnes, Intel Open Source Technology Center
On Mon, Oct 5, 2009 at 7:09 PM, Jesse Barnes <[email protected]> wrote:
>
> Gabe, did you figure out how to do this? ?Do you need any more help?
>
Yes, I have a patch tested and ready to go. Unfortunately, I'm
waiting on approval from the company I work at to submit it. I really
don't understand what they are so scared of; but they own me :-(
Hopefully it won't be much longer before they let me submit.
-- Gabe
This quirk will disable fast back to back transfer on the secondary bus
segment of the TI Bridge.
Signed-off-by: Gabe Black <[email protected]>
---
drivers/pci/quirks.c | 19 +++++++++++++++++++
include/linux/pci_ids.h | 1 +
2 files changed, 20 insertions(+), 0 deletions(-)
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 6099fac..efa6534 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -670,6 +670,25 @@ static void __devinit quirk_vt8235_acpi(struct pci_dev *dev)
}
DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8235, quirk_vt8235_acpi);
+/*
+ * TI XIO2000a PCIe-PCI Bridge erroneously reports it supports fast back-to-back:
+ * Disable fast back-to-back on the secondary bus segment
+ */
+static void __devinit quirk_xio2000a(struct pci_dev *dev)
+{
+ struct pci_dev *pdev;
+ u16 command;
+
+ dev_warn(&dev->dev, "TI XIO2000a quirk detected; "
+ "secondary bus fast back-to-back transfers disabled\n");
+ list_for_each_entry(pdev, &dev->subordinate->devices, bus_list) {
+ pci_read_config_word(pdev, PCI_COMMAND, &command);
+ if (command & PCI_COMMAND_FAST_BACK)
+ pci_write_config_word(pdev, PCI_COMMAND, command & ~PCI_COMMAND_FAST_BACK);
+ }
+}
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_TI, PCI_DEVICE_ID_TI_XIO2000A,
+ quirk_xio2000a);
#ifdef CONFIG_X86_IO_APIC
diff --git a/include/linux/pci_ids.h b/include/linux/pci_ids.h
index da1fda8..f490e7a 100644
--- a/include/linux/pci_ids.h
+++ b/include/linux/pci_ids.h
@@ -776,6 +776,7 @@
#define PCI_DEVICE_ID_TI_X515 0x8036
#define PCI_DEVICE_ID_TI_XX12 0x8039
#define PCI_DEVICE_ID_TI_XX12_FM 0x803b
+#define PCI_DEVICE_ID_TI_XIO2000A 0x8231
#define PCI_DEVICE_ID_TI_1130 0xac12
#define PCI_DEVICE_ID_TI_1031 0xac13
#define PCI_DEVICE_ID_TI_1131 0xac15
--
1.6.0.4
On Tue, 6 Oct 2009 09:19:45 -0500
Gabe Black <[email protected]> wrote:
> This quirk will disable fast back to back transfer on the secondary
> bus segment of the TI Bridge.
>
> Signed-off-by: Gabe Black <[email protected]>
Applied to my for-linus branch.
--
Jesse Barnes, Intel Open Source Technology Center