diff options
| author | Karsten Wiese <annabellesgarden@yahoo.de> | 2005-09-03 15:56:33 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@evo.osdl.org> | 2005-09-05 00:06:10 -0700 |
| commit | a1740913cae231fb8e485306fb09671ed9a6e550 (patch) | |
| tree | 60cde26b254d6df2433016cfa1f328b59b00b828 | |
| parent | 252943efcfce945d8dd3738ca4c4b9cbeb4f3fa9 (diff) | |
| download | linux-a1740913cae231fb8e485306fb09671ed9a6e550.tar.bz2 | |
[PATCH] via vt8237 apic bypass deassertion quirk
The VIA VT8237's IOAPIC sends 'APIC De-Assert Messages' by default, causing
another CPU interrupt when the IRQ pin is de-asserted. This feature is
switched off by the patch to get rid of doubled ioapic level interrupt
rates.
Signed-off-by: Karsten Wiese <annabellesgarden@yahoo.de>
Tested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | drivers/pci/quirks.c | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c index bb36bb69803f..140354a2aa72 100644 --- a/drivers/pci/quirks.c +++ b/drivers/pci/quirks.c @@ -422,6 +422,25 @@ static void __devinit quirk_via_ioapic(struct pci_dev *dev) DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_82C686, quirk_via_ioapic ); /* + * VIA 8237: Some BIOSs don't set the 'Bypass APIC De-Assert Message' Bit. + * This leads to doubled level interrupt rates. + * Set this bit to get rid of cycle wastage. + * Otherwise uncritical. + */ +static void __devinit quirk_via_vt8237_bypass_apic_deassert(struct pci_dev *dev) +{ + u8 misc_control2; +#define BYPASS_APIC_DEASSERT 8 + + pci_read_config_byte(dev, 0x5B, &misc_control2); + if (!(misc_control2 & BYPASS_APIC_DEASSERT)) { + printk(KERN_INFO "PCI: Bypassing VIA 8237 APIC De-Assert Message\n"); + pci_write_config_byte(dev, 0x5B, misc_control2|BYPASS_APIC_DEASSERT); + } +} +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_VIA, PCI_DEVICE_ID_VIA_8237, quirk_via_vt8237_bypass_apic_deassert); + +/* * The AMD io apic can hang the box when an apic irq is masked. * We check all revs >= B0 (yet not in the pre production!) as the bug * is currently marked NoFix |