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Subject[PATCH 4.4 102/241] dmaengine: pl330: _stop: clear interrupt status
Date
[ Upstream commit 2da254cc7908105a60a6bb219d18e8dced03dcb9 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/dma/pl330.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/dma/pl330.c b/drivers/dma/pl330.c
index 95619ee33112c..799c182c3eacc 100644
--- a/drivers/dma/pl330.c
+++ b/drivers/dma/pl330.c
@@ -1006,6 +1006,7 @@ static void _stop(struct pl330_thread *thrd)
{
void __iomem *regs = thrd->dmac->base;
u8 insn[6] = {0, 0, 0, 0, 0, 0};
+ u32 inten = readl(regs + INTEN);

if (_state(thrd) == PL330_STATE_FAULT_COMPLETING)
UNTIL(thrd, PL330_STATE_FAULTING | PL330_STATE_KILLING);
@@ -1018,10 +1019,13 @@ static void _stop(struct pl330_thread *thrd)

_emit_KILL(0, insn);

- /* Stop generating interrupts for SEV */
- writel(readl(regs + INTEN) & ~(1 << thrd->ev), regs + INTEN);
-
_execute_DBGINSN(thrd, insn, is_manager(thrd));
+
+ /* clear the event */
+ if (inten & (1 << thrd->ev))
+ writel(1 << thrd->ev, regs + INTCLR);
+ /* Stop generating interrupts for SEV */
+ writel(inten & ~(1 << thrd->ev), regs + INTEN);
}

/* Start doing req 'idx' of thread 'thrd' */
--
2.20.1


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