tree 12184b7ed8bea50f0ca10ff44c7f37e5c1bb0e07
parent 25e803f9c339a070cd7361e853aebde11b1f9217
author Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com> 1315296998 +0900
committer Grant Likely <grant.likely@secretlab.ca> 1317744650 -0600

spi-topcliff-pch: Fix overrun issue

We found that adding load, Rx data sometimes drops.(with DMA transfer mode)
The cause is that before starting Rx-DMA processing, Tx-DMA processing starts.
This causes FIFO overrun occurs.

This patch fixes the issue by modifying FIFO tx-threshold and DMA descriptor
size like below.

                      Current                   this patch
Rx-descriptor   4Byte+12Byte*341    -->    12Byte*340-4Byte-12Byte
Rx-threshold                   (Not modified)
Tx-descriptor   4Byte+12Byte*341    -->    16Byte-12Byte*340
Rx-threshold    12Byte              -->    2Byte

Signed-off-by: Tomoya MORINAGA <tomoya-linux@dsn.okisemi.com>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>