Commit 8f1e8ee2 authored Jan 16, 2015 by Thomas Petazzoni Committed by Andrew Lunn Jan 17, 2015

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>

parent eaa27f34

arch/arm/mach-mvebu/coherency.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -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)