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ARM: mvebu: completely disable hardware I/O coherency

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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>
This commit is contained in:
Thomas Petazzoni 2015-01-16 17:11:27 +01:00 committed by Andrew Lunn
parent eaa27f34e9
commit 8f1e8ee286
1 changed files with 6 additions and 1 deletions
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7
arch/arm/mach-mvebu/coherency.c
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@ -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)