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| author |   Thomas Petazzoni <thomas.petazzoni@free-electrons.com> | 2015-01-16 17:11:27 +0100 |
|---|---|---|
| committer |   Andrew Lunn <andrew@lunn.ch> | 2015-01-17 11:46:55 -0600 |
| commit | 8f1e8ee28660018a935c7576b9af8ffe1feab54c (patch) | |
| tree | 39ecf0922ae98ebbe7bc232076d65d849444af4c /arch/arm/mach-mvebu/coherency.c | |
| parent | linux 3.19-rc4 (diff) | |
| download | linux-dev-8f1e8ee28660018a935c7576b9af8ffe1feab54c.tar.xz linux-dev-8f1e8ee28660018a935c7576b9af8ffe1feab54c.zip | |
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/coherency.c')
| -rw-r--r-- | arch/arm/mach-mvebu/coherency.c | 7 |
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) |