[tip:x86/urgent] x86/quirks: Apply nvidia_bugs quirk only on root bus

[tip-bot for Lukas Wunner <tipbot@zytor.com>]

Commit-ID:  447d29d1d3aed839e74c2401ef63387780ac51ed
Gitweb:     http://git.kernel.org/tip/447d29d1d3aed839e74c2401ef63387780ac51ed
Author:     Lukas Wunner <lukas@wunner.de>
AuthorDate: Sun, 12 Jun 2016 12:31:53 +0200
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Sun, 10 Jul 2016 20:13:53 +0200

x86/quirks: Apply nvidia_bugs quirk only on root bus

Since the following 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.

Signed-off-by: Lukas Wunner <lukas@wunner.de>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yinghai Lu <yinghai@kernel.org>
Link: http://lkml.kernel.org/r/4d5477c1d76b2f0387a780f2142bbcdd9fee869b.1465690253.git.lukas@wunner.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 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.