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    SubjectRe: [PATCH 2.6.25-rc7 001/001] ACPI: workaround for buggy BIOS to ignore error LINK CRS method
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    On Wed, 2008-04-09 at 16:12 -0700, Andrew Morton wrote:
    > On Wed, 9 Apr 2008 17:42:34 +0200
    > NoWhereMan <uncommonnonsense@gmail.com> wrote:
    >
    > > >From : Edoardo Vacchi <uncommonnonsense@gmail.com>
    > >
    > > When acpi_pci_link_crs_ignore is passed at boot to the kernel,
    > > ignores the error about the _CRS method of LINK device and selects
    > > IRQ from possible IRQ list returned by _PRS method.
    > >
    > > Signed-off-by: Edoardo Vacchi <uncommonnonsense@gmail.com>
    > >
    >
    > Let's add some cc's.
    >
    > >
    > > This is nothing more than the patch on comment #127 on bug #8896
    > > http://bugzilla.kernel.org/show_bug.cgi?id=8896#c127
    > >
    > > originally by Zhao Yakui <yakui.zhao@intel.com>
    > >
    > > ported to 2.6.25 and wrapped into an additional check for the kernel parameter
    > > (plus of course the defintion of the kernel param itself)
    > >
    > > The patch provides a workaround for some buggy BIOSes such as Insyde
    > > in Packard Bell EasyNote r1938 (of which I'm an unfortunate owner),
    > > while still keeping boot safe for people not suffering from this bug
    > >
    >
    > That patch is about four months old. Hopefully there was a reason why we
    > dodn't proceed with it?
    It seems that the system can work after applying the patch.
    But the patch depends on the returned result(-ENODEV).
    > if (ACPI_FAILURE(status)) {
    > ACPI_EXCEPTION((AE_INFO, status, "Evaluating _CRS"));
    > result = -ENODEV;
    > goto end;
    > }
    Now I am writing another workaround patch about this problem.
    >
    > > diff --git a/drivers/acpi/pci_link.c b/drivers/acpi/pci_link.c
    > > index 233c40c..ed54c63 100644
    > > --- a/drivers/acpi/pci_link.c
    > > +++ b/drivers/acpi/pci_link.c
    > > @@ -297,6 +297,16 @@ static int acpi_pci_link_get_current(struct
    > > acpi_pci_link *link)
    > > return result;
    > > }
    > >
    > > +
    > > +/*
    > > + * this is set when acpi_pci_link_crs_ignore is passed on boot
    > > + * it will ignore the -ENODEV error on buggy BIOSes
    > > + *
    > > + * workaround for bug #8896
    > > + *
    > > + */
    > > +static int acpi_pci_link_crs_ignore; /* 0 or 1*/
    > > +
    > > static int acpi_pci_link_set(struct acpi_pci_link *link, int irq)
    > > {
    > > int result = 0;
    > > @@ -385,9 +395,16 @@ static int acpi_pci_link_set(struct acpi_pci_link
    > > *link, int irq)
    > >
    > > /* Query _CRS, set link->irq.active */
    > > result = acpi_pci_link_get_current(link);
    > > - if (result) {
    > > - goto end;
    > > - }
    > > + if (acpi_pci_link_crs_ignore && result == -ENODEV) {
    > > + /*
    > > + * Ignore the error about the _CRS method of Link device and
    > > + * select IRQ from the Possible IRQ list
    > > + * returned by _PRS method.
    > > + */
    > > + printk(KERN_WARNING "Ignore error LINK CRS method.\n");
    > > + link->irq.active = irq;
    > > + result = 0;
    > > + }
    > >
    > > /*
    > > * Is current setting not what we set?
    > > @@ -412,7 +429,16 @@ static int acpi_pci_link_set(struct acpi_pci_link
    > > *link, int irq)
    > > return result;
    > > }
    > >
    > > -/* --------------------------------------------------------------------------
    > > +int __init acpi_pci_link_crs_ignore_set(char *str)
    > > +{
    > > + acpi_pci_link_crs_ignore = 1;
    > > + return 1;
    > > +}
    > > +
    > > +__setup("acpi_pci_link_crs_ignore", acpi_pci_link_crs_ignore_set);
    > > +
    > > +
    > > + /* --------------------------------------------------------------------------
    > > PCI Link IRQ Management
    > > --------------------------------------------------------------------------
    > > */
    > > --
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