2015-04-27 11:52:23

by John Ogness

Subject: [PATCH 1/3] ARM: common: edma: clear completion interrupts on stop

When stopping a DMA transfer with interrupts disabled it is possible
that the DMA transfer completes before the events are cleared. In
this case the completion interrupt will be pending, causing a
completion callback after the transfer was stopped.

By clearing the completion interrupt for the stopping channel it is
ensured that no completion event will be generated after the stop.

Signed-off-by: John Ogness <[email protected]>
---
arch/arm/common/edma.c | 3 +++
1 file changed, 3 insertions(+)

diff --git a/arch/arm/common/edma.c b/arch/arm/common/edma.c
index 5662a87..873dbfc 100644
--- a/arch/arm/common/edma.c
+++ b/arch/arm/common/edma.c
@@ -1350,6 +1350,9 @@ void edma_stop(unsigned channel)
edma_shadow0_write_array(ctlr, SH_SECR, j, mask);
edma_write_array(ctlr, EDMA_EMCR, j, mask);

+ /* clear possibly pending completion interrupt */
+ edma_shadow0_write_array(ctlr, SH_ICR, j, mask);
+
pr_debug("EDMA: EER%d %08x\n", j,
edma_shadow0_read_array(ctlr, SH_EER, j));

--
1.7.10.4

2015-04-27 11:55:40

by Peter Ujfalusi

Subject: Re: [PATCH 1/3] ARM: common: edma: clear completion interrupts on stop

On 04/27/2015 02:52 PM, John Ogness wrote:
> When stopping a DMA transfer with interrupts disabled it is possible
> that the DMA transfer completes before the events are cleared. In
> this case the completion interrupt will be pending, causing a
> completion callback after the transfer was stopped.
>
> By clearing the completion interrupt for the stopping channel it is
> ensured that no completion event will be generated after the stop.

Acked-by: Peter Ujfalusi <[email protected]>


> Signed-off-by: John Ogness <[email protected]>
> ---
> arch/arm/common/edma.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/arch/arm/common/edma.c b/arch/arm/common/edma.c
> index 5662a87..873dbfc 100644
> --- a/arch/arm/common/edma.c
> +++ b/arch/arm/common/edma.c
> @@ -1350,6 +1350,9 @@ void edma_stop(unsigned channel)
> edma_shadow0_write_array(ctlr, SH_SECR, j, mask);
> edma_write_array(ctlr, EDMA_EMCR, j, mask);
>
> + /* clear possibly pending completion interrupt */
> + edma_shadow0_write_array(ctlr, SH_ICR, j, mask);
> +
> pr_debug("EDMA: EER%d %08x\n", j,
> edma_shadow0_read_array(ctlr, SH_EER, j));
>
>


--
P?ter