The hardware supports transfers up to a page boundary per buffer.
Currently, we work around that in the DMA code by splitting each
buffer up as we run through the scatterlist. Avoid this by telling
the block layers about the hardware restriction.
Eventually, this will allow us to phase out the splitting code,
but not until the old IDE layer allows us to control the value it
gives to blk_queue_segment_boundary().
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Move the definition of MAX_DMA_ADDRESS from mach/dma.h to mach/memory.h,
thereby placing it along side its relative, ISA_DMA_THRESHOLD.
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Let's provide an overridable default instead of having every machine
class define __virt_to_bus and __bus_to_virt to the same thing. What
most platforms are using is bus_addr == phys_addr so such is the default.
One exception is ebsa110 which has no DMA what so ever, so the actual
definition is not important except only for proper compilation. Also
added a comment about the special footbridge bus translation.
Let's also remove comments alluding to set_dma_addr which is not
(and should not) be commonly used.
Signed-off-by: Nicolas Pitre <nico@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
