diff options
| author | Thomas Petazzoni <thomas.petazzoni@free-electrons.com> | 2015-03-12 11:58:12 +0100 |
|---|---|---|
| committer | Sasha Levin <sasha.levin@oracle.com> | 2015-06-09 13:43:43 -0400 |
| commit | 43969ed3f1f84a000ba14443e78bdbce46a01103 (patch) | |
| tree | d15f148843ce3da9e9f2bd6287888ea51d51b833 /arch | |
| parent | 0c3d774dbb66ff74288bcd8a619d922e5214e2d7 (diff) | |
ARM: mvebu: do not register custom DMA operations when coherency is disabled
This patch is a partial backport of commit ef01c6c36bb8 ("ARM: mvebu:
remove Armada 375 Z1 workaround for I/O coherency"). This commit was
merged in v3.19, so kernel versions later than v3.19 are not affected
by the problem that this commit fixes.
It does not make a lot of sense to backport this commit entirely,
since it is mainly removing some no longer useful code. However, this
commit is also making sure that the bus_register_notifier that
register the custom DMA operations that should be used for HW I/O
coherency does not get registered when said HW I/O coherency is not
enabled.
This is particularly critical since we have decided to disable HW I/O
coherency completely in all kernels < 4.0, to be on the safe side,
while experimenting a new implementation of the HW I/O coherency in >=
4.0.
Without this commit, kernels earlier than 3.18 have the custom DMA
operations normally used for HW I/O coherency registered (they don't
do cache maintenance operations), while HW I/O coherency is
disabled. It essentially causes every DMA transfer to transfer
garbage.
The issue fixed by this commit was introduced by 5ab5afd8ba83 ("ARM:
mvebu: implement Armada 375 coherency workaround"), but it was not
visible until now since it didn't cause any problem when HW I/O
coherency is enabled.
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Cc: <stable@vger.kernel.org> v3.16..v3.18
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm/mach-mvebu/coherency.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c index 2ffccd4eb084..01efe130912e 100644 --- a/arch/arm/mach-mvebu/coherency.c +++ b/arch/arm/mach-mvebu/coherency.c @@ -448,8 +448,9 @@ static int __init coherency_late_init(void) armada_375_coherency_init_wa(); } - bus_register_notifier(&platform_bus_type, - &mvebu_hwcc_nb); + if (coherency_available()) + bus_register_notifier(&platform_bus_type, + &mvebu_hwcc_nb); return 0; } |