Re: AER/hotplug _OSC wierdness?

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Robert Hancock wrote:
I've been looking into why I get these messages on bootup on an Asus P7P55D PRO motherboard:

Firmware did not grant requested _OSC control
aer 0000:00:03.0:pcie02: AER service couldn't init device: no _OSC support
pci_hotplug: PCI Hot Plug PCI Core version: 0.5
Firmware did not grant requested _OSC control
Firmware did not grant requested _OSC control
Firmware did not grant requested _OSC control
Firmware did not grant requested _OSC control

The AML code for _OSC in the DSDT (below) is almost identical to the example code in the ACPI spec. From looking at the _OSC method, I don't see why it should reject any requests for PCI Express hotplug or AER control.

I can't quite make sense of the ACPI code that is supposed to handle this. When the AER driver calls acpi_pci_osc_control_set, it first does this:

    /* Need to query controls first before requesting them */
    if (!root->osc_queried) {
        status = acpi_pci_query_osc(root, root->osc_support_set);
        if (ACPI_FAILURE(status))
            goto out;
    }
    if ((root->osc_control_qry & control_req) != control_req) {
        printk(KERN_DEBUG
               "Firmware did not grant requested _OSC control\n");
        status = AE_SUPPORT;
        goto out;
    }

Inside acpi_pci_query_osc:

    /* do _OSC query for all possible controls */
    support_set = root->osc_support_set | (flags & OSC_SUPPORT_MASKS);
    capbuf[OSC_QUERY_TYPE] = OSC_QUERY_ENABLE;
    capbuf[OSC_SUPPORT_TYPE] = support_set;
    capbuf[OSC_CONTROL_TYPE] = OSC_CONTROL_MASKS;

    status = acpi_pci_run_osc(root->device->handle, capbuf, &result);
    if (ACPI_SUCCESS(status)) {
        root->osc_support_set = support_set;
        root->osc_control_qry = result;
        root->osc_queried = 1;
    }

The comment says "do _OSC query for all possible controls", but it doesn't look like that's what the code is actually doing. The first time this gets called, assuming osc_support_set is 0, it looks like support_set passed into _OSC will also be 0. Then osc_queried would be set to 1, _OSC would never get called again and the cached query result is based on 0 support flags being passed into _OSC, which is wrong. Or am I missing something?

    Name (PEHP, One)
    Name (SHPC, Zero)
    Name (PEPM, One)
    Name (PEER, One)
    Name (PECS, One)

...

        Method (_OSC, 4, NotSerialized)
        {
            Name (SUPP, Zero)
            Name (CTRL, Zero)
            CreateDWordField (Arg3, Zero, CDW1)
            CreateDWordField (Arg3, 0x04, CDW2)
            CreateDWordField (Arg3, 0x08, CDW3)
            If (LEqual (Arg0, Buffer (0x10)
                    {
/* 0000 */ 0x5B, 0x4D, 0xDB, 0x33, 0xF7, 0x1F, 0x1C, 0x40, /* 0008 */ 0x96, 0x57, 0x74, 0x41, 0xC0, 0x3D, 0xD7, 0x66
                    }))
            {
                Store (CDW2, SUPP)
                Store (CDW3, CTRL)
                If (LNotEqual (And (SUPP, 0x16), 0x16))
                {
                    And (CTRL, 0x1E, CTRL)
                }

                If (LNot (PEHP))
                {
                    And (CTRL, 0x1E, CTRL)
                }

                If (LNot (SHPC))
                {
                    And (CTRL, 0x1D, CTRL)
                }

                If (LNot (PEPM))
                {
                    And (CTRL, 0x1B, CTRL)
                }

                If (LNot (PEER))
                {
                    And (CTRL, 0x15, CTRL)
                }

                If (LNot (PECS))
                {
                    And (CTRL, 0x0F, CTRL)
                }

                If (Not (And (CDW1, One)))
                {
                    If (And (CTRL, One)) {}
                    If (And (CTRL, 0x04)) {}
                    If (And (CTRL, 0x10)) {}
                }

                If (LNotEqual (Arg1, One))
                {
                    Or (CDW1, 0x08, CDW1)
                }

                If (LNotEqual (CDW3, CTRL))
                {
                    Or (CDW1, 0x10, CDW1)
                }

                And (CTRL, 0xEF, CTRL)
                Store (CTRL, CDW3)

Your ACPI DSDT seems to clear "PCI Express Capability Structure
control" bit in returned value. Both AER and hotplug driver
requests this control. I think this is the reason why you
encountered "Firmware did not grant requested _OSC control".

Please double check.

Thanks,
Kenji Kaneshige


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