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    SubjectRe: [PATCH 1/1] PCI: tune up ICH4 quirk for broken BIOSes
    On 01/10/2011 07:40 PM, Bjorn Helgaas wrote:
    > On Saturday, January 08, 2011 02:58:01 am Jiri Slaby wrote:
    >> On 01/08/2011 01:16 AM, Bjorn Helgaas wrote:
    >>> On Friday, January 07, 2011 04:29:00 pm Jiri Slaby wrote:
    >>>> On 01/08/2011 12:03 AM, Bjorn Helgaas wrote:
    >>>>> On Friday, January 07, 2011 01:44:35 pm Jiri Slaby wrote:
    >>>>>> On 01/06/2011 08:24 PM, Bjorn Helgaas wrote:
    >>>>>>> Theoretically, ACPI tells us about the GPIO/TCO/etc. regions in a
    >>>>>>> generic way via namespace devices or something in the static tables.
    >>>>>>> Is that generic information missing, or is it there and Linux is
    >>>>>>> ignoring it? If we're ignoring it, I'd rather fix that.
    >>>>>> It works for most boxes I would say. Try to google for "claimed by ICH4
    >>>>>> ACPI/GPIO/TCO", it reports sane ranges like 0400-047f or 4000-407f.
    >>>>> My point is that BIOS should be telling the OS about GPIO/TCO/etc.
    >>>>> regions via an ACPI mechanism, and, ideally, we would use that rather
    >>>>> than reading the address out of chipset-dependent registers.
    >>>>> Even though PMBASE says the ACPI registers occupy 128 bytes from
    >>>>> 0x100-0x17f, it's likely there's no actual conflict between the
    >>>>> last 16 bytes and the IDE device.
    >>>> I wouldn't say so. According to the datasheet 0x60-0x7f of the space
    >>>> (i.e. 0x160-0x17f here) is for TCO registers. There:
    >>>> 0x10 -- Software IRQ Generation Register (i.e. 0x170)
    >>>> 0x11-0x1f -- reserved (0x171-0x17f)
    >>>> So at least 0x170 should be conflicting. Unless TCO is unused/disabled
    >>>> and not mapped there at all. May be that the case?
    >>> Maybe. All your patch does is avoid reserving this 0x100-0x1f7
    >>> region; it doesn't actually *move* anything. And the IDE device
    >>> apparently works at the 0x170 compatibility address. So the
    >>> ICH ACPI stuff is still at 0x100-0x17f, so apparently they don't
    >>> conflict or maybe the ICH ACPI stuff is disabled. If the box
    >>> doesn't even have ACPI, I suppose there would be no reason to
    >>> have the ACPI registers enabled. Is there something in ICH
    >>> that tells us whether they're enabled?
    >> Hmm, there is:
    >> bit 4: ACPI Enable (ACPI_EN) — R/W.
    >> 0 = Disable.
    >> 1 = Decode of the I/O range pointed to by the ACPI Base register is
    >> enabled, and the ACPI power management function is enabled. Note that
    >> the APM power management ranges (B2/B3h) are always enabled and are not
    >> affected by this bit.
    >> at 0x44 in the bridge conf space. So we should definitely check the value.
    >> I don't have the actual value in that register when ACPI is disabled in
    >> BIOS. From the run where acpi=off was passed to the kernel, there is
    >> 0x10 (i.e. ACPI_EN=1). However I don't know whether ACPI was disabled in
    >> BIOS at that time.
    > Checking ACPI_EN before doing anything in the quirk looks like
    > the simplest thing (if the BIOS actually sets ACPI_EN=0 when
    > it disables ACPI).

    Unfortunately, they double checked and the BIOS leaves ACPI_EN=1 even
    when ACPI is disabled.
    From hexdump -Cv /sys/bus/pci/devices/0000\:00\:1f.0/config:
    00000040 01 01 00 00 10 00 00 00 00 00 00 00 00 00 01 00
    ^base addr^|^-- 4th bit ~ ACPI_EN

    But I think we still should add the check in any case, the same for GPIO
    (there is GPIO_EN) and maybe for newer ICHs. What do you think?

    The problem is we can't add a quirk based on DMI for this one, since
    there is no DMI table.

    I'm out of ideas now.

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      Last update: 2011-01-13 11:13    [W:0.029 / U:0.056 seconds]
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