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Commit 1f20756c authored by Thomas Petazzoni's avatar Thomas Petazzoni Committed by Greg Kroah-Hartman
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ARM: mvebu: completely disable hardware I/O coherency 



commit 8f1e8ee28660018a935c7576b9af8ffe1feab54c upstream.

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: default avatarThomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: default avatarAndrew Lunn <andrew@lunn.ch>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7b915d38

arch/arm/mach-mvebu/coherency.c

+6 −1
Original line number Diff line number Diff line
@@ -398,9 +398,14 @@ 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)