ARC: dma [non IOC]: fix arc_dma_sync_single_for_(device|cpu)
authorEugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Tue, 24 Jul 2018 14:13:02 +0000 (17:13 +0300)
committerVineet Gupta <vgupta@synopsys.com>
Fri, 27 Jul 2018 20:12:40 +0000 (13:12 -0700)
commit4c612add7b18844ddd733ebdcbe754520155999b
tree9e21f86905d7924adb22b75512fe4fecf4a2d086
parent6d20caed9b92d0db005324281e10bb9fd4813a32
ARC: dma [non IOC]: fix arc_dma_sync_single_for_(device|cpu)

ARC backend for dma_sync_single_for_(device|cpu) was broken as it was
not honoring the @dir argument and simply forcing it based on the call:
 - arc_dma_sync_single_for_device(dir) assumed DMA_TO_DEVICE (cache wback)
 - arc_dma_sync_single_for_cpu(dir) assumed DMA_FROM_DEVICE (cache inv)

This is not true given the DMA API programming model and has been
discussed here [1] in some detail.

Interestingly while the deficiency has been there forever, it only started
showing up after 4.17 dma common ops rework, commit a8eb92d02dd7
("arc: fix arc_dma_{map,unmap}_page") which wired up these calls under the
more commonly used dma_map_page API triggering the issue.

[1]: https://lkml.org/lkml/2018/5/18/979
Fixes: commit a8eb92d02dd7 ("arc: fix arc_dma_{map,unmap}_page")
Cc: stable@kernel.org # v4.17+
Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>
[vgupta: reworked changelog]
arch/arc/mm/dma.c