linux-kernel - Re: [PATCH 2/2] dma: tegra: do not set transfer desc flag to DMA_CTRL

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Date:	Fri, 22 Jun 2012 11:10:25 -0600
From:	Stephen Warren <swarren@...dotorg.org>
To:	Laxman Dewangan <ldewangan@...dia.com>
CC:	vinod.koul@...el.com, dan.j.williams@...el.com,
	linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org
Subject: Re: [PATCH 2/2] dma: tegra: do not set transfer desc flag to DMA_CTRL_ACK
 in cyclic mode

On 06/22/2012 05:42 AM, Laxman Dewangan wrote:
> The sound dmaengine pcm driver uses the dma in cyclic mode and
> it does not ack the transfer descriptor  after transfer stops.
> This may lead to hold that desc in chip's dma driver and does
> not allow to reuse/free that descriptors. Hence not enabling
> flag DMA_CTRL_ACK when dma runs in cyclic mode.

> diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
> @@ -1093,7 +1093,7 @@ struct dma_async_tx_descriptor *tegra_dma_prep_dma_cyclic(
> -	dma_desc->txd.flags = DMA_CTRL_ACK;
> +	dma_desc->txd.flags = 0;

I honestly have no idea about this one. If the dmaengine maintainers
think it's semantically correct, I have no objections.
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