[PATCH v2 1/3] x86/quirks: Apply nvidia_bugs quirk only on root bus

[Lukas Wunner <lukas@wunner.de>]

Since commit 8659c406ade3 ("x86: only scan the root bus in early PCI
quirks"), early quirks are only applied to devices on the root bus.
The motivation was to prevent application of the nvidia_bugs quirk on
secondary buses.

We're about to reintroduce scanning of secondary buses for a quirk to
reset the Broadcom 4331 wireless card on 2011/2012 Macs. To prevent
regressions, open code the requirement to apply nvidia_bugs only on the
root bus.

Cc: Andi Kleen <ak@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
---
v2:
  - Move amendment of nvidia_bugs quirk to separate patch to allow for
    easier reviewing, bisecting and reverting (Bjorn Helgaas)

 arch/x86/kernel/early-quirks.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/arch/x86/kernel/early-quirks.c b/arch/x86/kernel/early-quirks.c
index bca14c8..256976f 100644
--- a/arch/x86/kernel/early-quirks.c
+++ b/arch/x86/kernel/early-quirks.c
@@ -76,6 +76,13 @@ static void __init nvidia_bugs(int num, int slot, int func)
 #ifdef CONFIG_ACPI
 #ifdef CONFIG_X86_IO_APIC
 	/*
+	 * Only applies to Nvidia root ports (bus 0) and not to
+	 * Nvidia graphics cards with PCI ports on secondary buses.
+	 */
+	if (num)
+		return;
+
+	/*
 	 * All timer overrides on Nvidia are
 	 * wrong unless HPET is enabled.
 	 * Unfortunately that's not true on many Asus boards.
-- 
2.8.1