On Thursday, January 13, 2011 03:07:24 am Jiri Slaby wrote: > 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) â 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. I think we're back to the question of why we have the ICH4 quirk in the first place, and I don't know the answer to that. If we didn't have the quirk at all, this machine would work. Other machines *should* work without, but maybe there's a BIOS or old Linux bug that the quirk covers up. I added Linus because he added some similar "should be unnecessary" code for ICH7+ (894886e5d). Maybe you could make the ICH4 quirk only claim the region if it's above PCIBIOS_MIN_IO, i.e., if it's in the area where we could put another PCI device on top of it? Bjorn -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
