linux-kernel - Re: [PATCH] dma: pl330: Add support for DMA

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Message-ID: <CABb+yY3YocX=8Dv7DysM4tcx=NTCCGGipz_gpMfpKDnAw7R8iw@mail.gmail.com>
Date:	Wed, 14 May 2014 17:29:05 +0530
From:	Jassi Brar <jassisinghbrar@...il.com>
To:	Tushar Behera <tushar.behera@...aro.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	dmaengine@...r.kernel.org, Vinod Koul <vinod.koul@...el.com>,
	Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH] dma: pl330: Add support for DMA_PAUSE command

On Wed, May 14, 2014 at 8:53 AM, Tushar Behera <tushar.behera@...aro.org> wrote:
> While playing back audio, pmc_dmaengine requests the DMA channel to
> stop DMA transmission through DMA_PAUSE command.
>
> Currently PL330 driver doesn't support DMA pause command, leaving
> the DMA state inconsistent when the system resumes. Instead, it would
> be better to terminate the DMA transfer during suspend and restart
> again during resume.
>
> Tested with audio playback across a suspend-resume cycle.
>
What is pmc_dmaengine? How does DMA_PAUSE help, when there is no DMA_RESUME?

DMA_PAUSE means freezing the transfer, not dropping it. DMA_RESUME
then moves the transfer again from that point. Clubbing PAUSE with
TERMINATE is plain wrong.  Sorry.

Regards
Jassi
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