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    SubjectRe: "do_IRQ: 0.89 No irq handler for vector (irq -1)"
    On Tue, 12 Oct 2010 12:49:38 -0700
    Jesse Barnes <jbarnes@virtuousgeek.org> wrote:

    > On Tue, 12 Oct 2010 21:01:17 +0200
    > "Rafael J. Wysocki" <rjw@sisk.pl> wrote:
    >
    > > On Tuesday, October 12, 2010, Jesse Barnes wrote:
    > > > On Mon, 11 Oct 2010 15:48:26 -0700
    > > > Jesse Barnes <jbarnes@virtuousgeek.org> wrote:
    > > >
    > > > > On Fri, 8 Oct 2010 21:46:50 +1000
    > > > > Dave Airlie <airlied@gmail.com> wrote:
    > > > > > Not sure how best to fix, I can workaround by calling
    > > > > > pci_set_power_state(PCI_D0) in the drm drivers, but I sorta thing the
    > > > > > PCI layer should take care of this.
    > > > >
    > > > > So I think we *should* be able to call pci_disable_device at remove
    > > > > time. But as you say, some platforms may not correctly re-route VGA
    > > > > space to an existing device or disable it properly when we do that.
    > > > > AFAICT x86 will be ok here though (seems to work ok locally too).
    > > >
    > > > Just tested this some more, and I think it's the right thing to do in
    > > > the KMS case at least. When we load a KMS driver it takes over the gfx
    > > > device and nothing can assume anything about VGA state unless using the
    > > > VGA arbiter. So calling pci_disable_device() in the shutdown path of a
    > > > KMS driver shouldn't make things any worse, and will work around this
    > > > issue.
    > > >
    > > > Doing so in the non-KMS case violates some PC assumptions though, in
    > > > that things like vgacon and the BIOS will assume VGA memory is still
    > > > around, which on some platforms pci_disable_device() may affect (I only
    > > > checked the x86 implementation).
    > > >
    > > > > That said, it seems like we should update the current device state at
    > > > > load time as well, once we've matched the driver it seems like there
    > > > > should be no harm.
    > > > >
    > > > > Rafael, what do you think? Would having the correct power state at
    > > > > load time cause any trouble with other PM code? I know we've had
    > > > > issues with setting it explicitly in the past...
    > > >
    > > > So we should probably make pci_enable_device pick up the current state
    > > > as well, instead of assuming it's unknown just because the enable count
    > > > was non-zero (which as Dave points out, can be affected by sysfs writes
    > > > too).
    > > >
    > > > The only downside I can think of there is that if the device is already
    > > > enabled, we generally have to assume another driver owns it, and who
    > > > knows if the device is actually alive enough to read the current state
    > > > from. But I think we handle those errors ok too, so pulling it out
    > > > should be safe.
    > >
    > > I remember trying to do something like this and it didn't play well with the
    > > initialization. Still, I didn't do that in pci_enable_device(), so I can't say
    > > for sure at the moment. I _think_ it will be fine, though.
    >
    > Seems to work ok for the buggy i915 reload case. But looking at it
    > again, I really don't like two things:
    > 1) doing just the set_power_state seems wrong, what about the rest of
    > enable?
    > 2) allowing nested enables at all
    >
    > I know sysfs currently allows us to bump the enable count to arbitrary
    > levels, but that's easy to fix; we can just check pci_is_enabled()
    > before calling enable_device in the sysfs store routine.
    >
    > If we did that, we could warn when pci_enable_device is called in a
    > nested way, which is generally a bug (two drivers trying to take over a
    > device?).
    >
    > I don't think I buy that VGA is special anyway, at least not for KMS
    > enabled kernels, where vgacon and the BIOS can't assume anything about
    > graphics state anymore. More generally, I don't think BIOSes have been
    > able to assume anything about the current graphics state since Windows
    > 3.1, when most platforms stopped using BIOS calls and/or VGA regs for
    > mode setting.
    >
    > Thoughts?
    >

    does this need to go to 2.6.36.y? (is it already on it's way?)

    commit 97c145f7c87453cec90e91238fba5fe2c1561b32
    Author: Jesse Barnes <jbarnes@virtuousgeek.org>
    Date: Fri Nov 5 15:16:36 2010 -0400

    PCI: read current power state at enable time



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