[PATCH] arm: mvebu: fix coherency_late_init() for multiplatform

[Thomas Petazzoni]

As noticed by Arnaud Patard (Rtp) <arnaud.patard at rtp-net.org>, commit
865e0527d2d7 ('arm: mvebu: avoid hardcoded virtual address in
coherency code') added a postcore_initcall() to register the bus
notifier that the mvebu code needs to apply correct DMA operations on
its platform devices breaks the multiplatform boot on other platforms,
because the bus notifier registration is unconditional.

This commit fixes that by registering the bus notifier only if we have
the mvebu coherency unit described in the Device Tree. The conditional
used is exactly the same in which the bus_register_notifier() call was
originally enclosed before 865e0527d2d7 ('arm: mvebu: avoid hardcoded
virtual address in coherency code').

Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
Reported-by: Arnaud Patard (Rtp) <arnaud.patard at rtp-net.org>
---
This fix has been reported by Arnaud to fix the boot on his OMAP4
PandaBoard, and it continues to work well on Marvell Armada XP GP.

This commit is based on jcooper/mvebu/regmap.
---
 arch/arm/mach-mvebu/coherency.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c
index 32fcf69..be11759 100644
--- a/arch/arm/mach-mvebu/coherency.c
+++ b/arch/arm/mach-mvebu/coherency.c
@@ -147,8 +147,9 @@ int __init coherency_init(void)
 
 static int __init coherency_late_init(void)
 {
-	bus_register_notifier(&platform_bus_type,
-			      &mvebu_hwcc_platform_nb);
+	if (of_find_matching_node(NULL, of_coherency_table))
+		bus_register_notifier(&platform_bus_type,
+				      &mvebu_hwcc_platform_nb);
 	return 0;
 }
 
-- 
1.8.1.2