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authorThomas Petazzoni <thomas.petazzoni@free-electrons.com>2015-01-16 17:11:27 +0100
committerAndrew Lunn <andrew@lunn.ch>2015-01-17 11:46:55 -0600
commit8f1e8ee28660018a935c7576b9af8ffe1feab54c (patch)
tree39ecf0922ae98ebbe7bc232076d65d849444af4c /arch/arm/mach-mvebu
parenteaa27f34e91a14cdceed26ed6c6793ec1d186115 (diff)
ARM: mvebu: completely disable hardware I/O coherency
The current hardware I/O coherency is known to cause problems with DMA coherent buffers, as it still requires explicit I/O synchronization barriers, which is not compatible with the semantics expected by the Linux DMA coherent buffers API. So, in order to have enough time to validate a new solution based on automatic I/O synchronization barriers, this commit disables hardware I/O coherency entirely. Future patches will re-enable it. Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Cc: <stable@vger.kernel.org> # v3.8+ Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Diffstat (limited to 'arch/arm/mach-mvebu')
-rw-r--r--arch/arm/mach-mvebu/coherency.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/arm/mach-mvebu/coherency.c b/arch/arm/mach-mvebu/coherency.c
index 3585cb394e9b..caa21e9b8cd9 100644
--- a/arch/arm/mach-mvebu/coherency.c
+++ b/arch/arm/mach-mvebu/coherency.c
@@ -246,9 +246,14 @@ static int coherency_type(void)
return type;
}
+/*
+ * As a precaution, we currently completely disable hardware I/O
+ * coherency, until enough testing is done with automatic I/O
+ * synchronization barriers to validate that it is a proper solution.
+ */
int coherency_available(void)
{
- return coherency_type() != COHERENCY_FABRIC_TYPE_NONE;
+ return false;
}
int __init coherency_init(void)