[PATCH] x86: Disable HPET MSI on ATI SB700/SB800

["Pallipadi, Venkatesh" <venkatesh.pallipadi@intel.com>]

HPET MSI on platforms with ATI SB700/SB800 as they seem to have some
side-effects on floppy DMA. Do not use HPET MSI on such platforms.

Original problem report from Mark Hounschell
http://lkml.indiana.edu/hypermail/linux/kernel/0912.2/01118.html

Tested-by: Mark Hounschell <markh@compro.net>

Signed-off-by: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
---

This patch needs to go to stable as well. But, there are some conflicts that prevents
the patch from going as is. I can rebase/resubmit to stable once the patch goes upstream.

 arch/x86/include/asm/hpet.h |    1 +
 arch/x86/kernel/hpet.c      |    8 ++++++++
 arch/x86/kernel/quirks.c    |   13 +++++++++++++
 3 files changed, 22 insertions(+), 0 deletions(-)

diff --git a/arch/x86/include/asm/hpet.h b/arch/x86/include/asm/hpet.h
index 5d89fd2..1d5c08a 100644
--- a/arch/x86/include/asm/hpet.h
+++ b/arch/x86/include/asm/hpet.h
@@ -67,6 +67,7 @@ extern unsigned long hpet_address;
 extern unsigned long force_hpet_address;
 extern u8 hpet_blockid;
 extern int hpet_force_user;
+extern u8 hpet_msi_disable;
 extern int is_hpet_enabled(void);
 extern int hpet_enable(void);
 extern void hpet_disable(void);
diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index ba6e658..ad80a1c 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -34,6 +34,8 @@
  */
 unsigned long				hpet_address;
 u8					hpet_blockid; /* OS timer block num */
+u8					hpet_msi_disable;
+
 #ifdef CONFIG_PCI_MSI
 static unsigned long			hpet_num_timers;
 #endif
@@ -596,6 +598,9 @@ static void hpet_msi_capability_lookup(unsigned int start_timer)
 	unsigned int num_timers_used = 0;
 	int i;
 
+	if (hpet_msi_disable)
+		return;
+
 	if (boot_cpu_has(X86_FEATURE_ARAT))
 		return;
 	id = hpet_readl(HPET_ID);
@@ -928,6 +933,9 @@ static __init int hpet_late_init(void)
 	hpet_reserve_platform_timers(hpet_readl(HPET_ID));
 	hpet_print_config();
 
+	if (hpet_msi_disable)
+		return 0;
+
 	if (boot_cpu_has(X86_FEATURE_ARAT))
 		return 0;
 
diff --git a/arch/x86/kernel/quirks.c b/arch/x86/kernel/quirks.c
index 18093d7..12e9fea 100644
--- a/arch/x86/kernel/quirks.c
+++ b/arch/x86/kernel/quirks.c
@@ -491,6 +491,19 @@ void force_hpet_resume(void)
 		break;
 	}
 }
+
+/*
+ * HPET MSI on some boards (ATI SB700/SB800) has side effect on
+ * floppy DMA. Disable HPET MSI on such platforms.
+ */
+static void force_disable_hpet_msi(struct pci_dev *unused)
+{
+	hpet_msi_disable = 1;
+}
+
+DECLARE_PCI_FIXUP_HEADER(PCI_VENDOR_ID_ATI, PCI_DEVICE_ID_ATI_SBX00_SMBUS,
+			 force_disable_hpet_msi);
+
 #endif
 
 #if defined(CONFIG_PCI) && defined(CONFIG_NUMA)
-- 
1.6.0.6