linux-kernel - Re: [RESEND PATCH v2 1/1] ASoC: dwc: fix dma stop transferring issue

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Date:	Wed, 30 Sep 2015 19:22:19 +0100
From:	Mark Brown <broonie@...nel.org>
To:	yitian <yitian.bu@...gramtek.com>
Cc:	lgirdwood@...il.com, perex@...ex.cz, tiwai@...e.com,
	Andrew.Jackson@....com, wsa@...-dreams.de,
	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [RESEND PATCH v2 1/1] ASoC: dwc: fix dma stop transferring issue

On Tue, Sep 29, 2015 at 10:43:17PM +0800, yitian wrote:
> Designware I2S uses tx empty and rx available signals as the DMA
> handshaking signals. during music playing, if XRUN occurs,
> i2s_stop() function will be executed and both tx and rx irq are
> masked, when music continues to be played, i2s_start() is executed
> but both tx and rx irq are not unmasked which cause I2S stop
> sending DMA handshaking signal to DMA controller, and it finally
> causes music playing will be stopped once XRUN occurs for the first
> time.

I'm a bit concerned about how this code ever worked given the above
description - is there some race condition which allows things to work
if we're lucky?

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