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

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Date:	Mon, 27 Apr 2015 14:55:26 +0300
From:	Peter Ujfalusi <peter.ujfalusi@...com>
To:	John Ogness <john.ogness@...utronix.de>,
	<linux-kernel@...r.kernel.org>
CC:	<linux-serial@...r.kernel.org>, Sekhar Nori <nsekhar@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
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 <peter.ujfalusi@...com>


> Signed-off-by: John Ogness <john.ogness@...utronix.de>
> ---
>  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));
>  
> 


-- 
Péter
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