linux-kernel - [PATCH] x86: SB450: skip IRQ0 override if it is not routed to INT2 of IOAPIC

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Message-ID: <20081006221122.GC22097@alberich.amd.com>
Date:	Tue, 7 Oct 2008 00:11:22 +0200
From:	Andreas Herrmann <andreas.herrmann3@....com>
To:	"Maciej W. Rozycki" <macro@...ux-mips.org>
CC:	Andi Kleen <andi@...stfloor.org>, Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Len Brown <lenb@...nel.org>,
	Jason Vas Dias <jason.vas.dias@...il.com>
Subject: [PATCH] x86: SB450: skip IRQ0 override if it is not routed to INT2
	of IOAPIC

On Mon, Oct 06, 2008 at 10:39:25PM +0100, Maciej W. Rozycki wrote:
> On Mon, 6 Oct 2008, Andi Kleen wrote:
> 
> > The real reason is actually a workaround in the BIOS for problems
> > in the older Linux code that caused duplicated timer interrupts. The
> > old Linux would fall into "enable both IO-APIC and 8259" fallback mode
> > and the resulted in duplicated timer events, which made everything unhappy.
> > They instead configured the northbridge in a way that one of the inputs
> > is ignored.
> 
>  Hmm, working around Linux problems in the BIOS is a new and truly odd 
> concept to me.  It's not that we are unresponsive or do not take 
> responsibility for our bugs, is it?

So, let's work around BIOS bugs in Linux then ...

Following patch is almost untested -- especially I didn't get my
hands on one of the HP Laptops with broken DSDT.


Regards,

Andreas

--

On some HP nx6... laptops (e.g. nx6325) BIOS reports an IRQ0 override
but the SB450 chipset is configured such that timer interrupts goe to
INT0 of IOAPIC.

Check IRQ0 routing and if it is routed to INT0 of IOAPIC skip the
timer override.

Signed-off-by: Andreas Herrmann <andreas.herrmann3@....com>
---
 arch/x86/kernel/early-quirks.c |   48 ++++++++++++++++++++++++++++++++++++++++
 1 files changed, 48 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
index 4353cf5..6b839b1 100644
--- a/arch/x86/kernel/early-quirks.c
+++ b/arch/x86/kernel/early-quirks.c
@@ -95,6 +95,52 @@ static void __init nvidia_bugs(int num, int slot, int func)
 
 }
 
+static u32 ati_ixp4x0_rev(int num, int slot, int func)
+{
+	u32 d;
+	u8  b;
+
+	b = read_pci_config_byte(num, slot, func, 0xac);
+	b &= ~(1<<5);
+	write_pci_config_byte(num, slot, func, 0xac, b);
+
+	d = read_pci_config(num, slot, func, 0x70);
+	d |= 1<<8;
+	write_pci_config(num, slot, func, 0x70, d);
+
+	d = read_pci_config(num, slot, func, 0x8);
+	d &= 0xff;
+	return d;
+}
+
+static void __init ati_bugs(int num, int slot, int func)
+{
+#if defined(CONFIG_ACPI) && defined (CONFIG_X86_IO_APIC)
+	u32 d;
+	u8  b;
+
+	if (acpi_use_timer_override)
+		return;
+
+	d = ati_ixp4x0_rev(num, slot, func);
+	if (d  < 0x82)
+		acpi_skip_timer_override = 1;
+	else {
+		/* check for IRQ0 interrupt swap */
+		outb(0x72, 0xcd6); b = inb(0xcd7);
+		if (!(b & 0x2))
+			acpi_skip_timer_override = 1;
+	}
+
+	if (acpi_skip_timer_override) {
+		printk(KERN_INFO "SB4X0 revision 0x%x\n", d);
+		printk(KERN_INFO "Ignoring ACPI timer override.\n");
+		printk(KERN_INFO "If you got timer trouble "
+		       "try acpi_use_timer_override\n");
+	}
+#endif
+}
+
 #define QFLAG_APPLY_ONCE 	0x1
 #define QFLAG_APPLIED		0x2
 #define QFLAG_DONE		(QFLAG_APPLY_ONCE|QFLAG_APPLIED)
@@ -114,6 +160,8 @@ static struct chipset early_qrk[] __initdata = {
 	  PCI_CLASS_BRIDGE_PCI, PCI_ANY_ID, QFLAG_APPLY_ONCE, via_bugs },
 	{ PCI_VENDOR_ID_AMD, PCI_DEVICE_ID_AMD_K8_NB,
 	  PCI_CLASS_BRIDGE_HOST, PCI_ANY_ID, 0, fix_hypertransport_config },
+	{ PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_IXP400_SMBUS,
+	  PCI_CLASS_SERIAL_SMBUS, PCI_ANY_ID, 0, ati_bugs },
 	{}
 };
 
-- 
1.6.0.2



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