dmaengine: pl330: _stop: clear interrupt status
authorSugar Zhang <sugar.zhang@rock-chips.com>
Wed, 3 Apr 2019 11:06:22 +0000 (19:06 +0800)
committerVinod Koul <vkoul@kernel.org>
Fri, 26 Apr 2019 11:21:37 +0000 (16:51 +0530)
commit2da254cc7908105a60a6bb219d18e8dced03dcb9
tree0d58d112ce9b0c64f73b4f24e0d3b0092891a83c
parent9a05045d2a681d36c80aafc08d9d0b63d4ddbc66
dmaengine: pl330: _stop: clear interrupt status

This patch kill instructs the DMAC to immediately terminate
execution of a thread. and then clear the interrupt status,
at last, stop generating interrupts for DMA_SEV. to guarantee
the next dma start is clean. otherwise, one interrupt maybe leave
to next start and make some mistake.

we can reporduce the problem as follows:

DMASEV: modify the event-interrupt resource, and if the INTEN sets
function as interrupt, the DMAC will set irq<event_num> HIGH to
generate interrupt. write INTCLR to clear interrupt.

DMA EXECUTING INSTRUCTS DMA TERMINATE
| |
| |
       ...       _stop
| |
| spin_lock_irqsave
     DMASEV |
| |
|     mask INTEN
| |
|      DMAKILL
| |
| spin_unlock_irqrestore

in above case, a interrupt was left, and if we unmask INTEN, the DMAC
will set irq<event_num> HIGH to generate interrupt.

to fix this, do as follows:

DMA EXECUTING INSTRUCTS DMA TERMINATE
| |
| |
       ...       _stop
| |
| spin_lock_irqsave
     DMASEV |
| |
|      DMAKILL
| |
|    clear INTCLR
|     mask INTEN
| |
| spin_unlock_irqrestore

Signed-off-by: Sugar Zhang <sugar.zhang@rock-chips.com>
Signed-off-by: Vinod Koul <vkoul@kernel.org>
drivers/dma/pl330.c