Fix synchronization issues found during testing using multiple DMA
transfer requests to the same channel:
- lost MSI-X interrupt notifications
- non-synchronized attempts to start DMA channel HW resulting in error
message from the driver
- cookie tracking/update race conditions resulting in incorrect DMA
transfer status report
Signed-off-by: Alexandre Bounine <alexandre.bounine@idt.com> Reported-by: Barry Wood <barry.wood@idt.com> Tested-by: Barry Wood <barry.wood@idt.com> Cc: Matt Porter <mporter@kernel.crashing.org> Cc: Aurelien Jacquiot <a-jacquiot@ti.com> Cc: Andre van Herk <andre.van.herk@prodrive-technologies.com> Cc: Barry Wood <barry.wood@idt.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>