linux-wandboard

MLK-11344-9: dma: imx-sdma: A bungle of work around for BUG ON issue

cherry-pick below patch from v3.14.y:
ENGR00313512 dma: imx-sdma: A bungle of work around for
 BUG ON issue

The BUG ON issue could be triggered by such scenarios:

A)
issue_pending(1) ->
                <- SDMA irq(1)
                <- SDMA tasklet(1)   //Normal case
issue_pending(2) ->
terminate_all(2) ->
... system suspend/resume
issue_pending(3) ->
                <- SDMA irq(2)
                <- SDMA irq(3)     //might also happen after tasklet(2)
                <- SDMA tasklet(2)
                <- SDMA tasklet(3) //BUG ON

B)
issue_pending(1) ->
                <- SDMA irq(1)
                <- SDMA tasklet(1)   //Normal case
issue_pending(2) ->
                <- SDMA irq(2)   //might also happen after terminate_all(2)
terminate_all(2) ->
... system suspend/resume
issue_pending(3) ->
                <- SDMA irq(3)     //might also happen after tasklet(2)
                <- SDMA tasklet(2)
                <- SDMA tasklet(3) //BUG ON

The best fix for this issue is to eradicate irq(2) or tasklet(2).

However, currently we couldn't find an effective fix for both cases above.

Thus this fix could be treated as a work around. It fixes this issue by Reduce
the possiblity of irq(2) and tasklet(3).

Signed-off-by: Nicolin Chen <Guangyu.Chen@freescale.com>
Signed-off-by: Robin Gong <b38343@freescale.com>
(cherry picked from commit 1880fc41df51450825c2b17bae5be9536e26b73f)
(cherry picked from commit a744dfb31122b8393e717e8a6911b221d1d49052)