linux-kernel - [PATCH] sound: soc: atmel: Don't unconditionally reset SSC on stream startup

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Message-Id: <20160810101422.2086-1-pmeerw@pmeerw.net>
Date:	Wed, 10 Aug 2016 12:14:22 +0200
From:	Peter Meerwald <pmeerw@...erw.net>
To:	Mark Brown <broonie@...nel.org>
Cc:	alsa-devel@...a-project.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Christoph Huber <c.huber@...-electronic.com>,
	Peter Meerwald-Stadler <p.meerwald@...-electronic.com>,
	Songjun Wu <songjun.wu@...rochip.com>,
	Nicolas Ferre <nicolas.ferre@...el.com>
Subject: [PATCH] sound: soc: atmel: Don't unconditionally reset SSC on stream startup

From: Christoph Huber <c.huber@...-electronic.com>

commit cbaadf0f90d6 (ASoC: atmel_ssc_dai: refactor the startup and shutdown)
refactored code such that the SSC is reset on every startup;
this breaks duplex audio (e.g. first start audio playback, then start record,
causing the playback to stop/hang)

Signed-off-by: Christoph Huber <c.huber@...-electronic.com>
Signed-off-by: Peter Meerwald-Stadler <p.meerwald@...-electronic.com>
Cc: Songjun Wu <songjun.wu@...rochip.com>
Cc: Nicolas Ferre <nicolas.ferre@...el.com>
---
 sound/soc/atmel/atmel_ssc_dai.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/sound/soc/atmel/atmel_ssc_dai.c b/sound/soc/atmel/atmel_ssc_dai.c
index 841d059..b3e9f0c 100644
--- a/sound/soc/atmel/atmel_ssc_dai.c
+++ b/sound/soc/atmel/atmel_ssc_dai.c
@@ -298,8 +298,9 @@ static int atmel_ssc_startup(struct snd_pcm_substream *substream,
 	clk_enable(ssc_p->ssc->clk);
 	ssc_p->mck_rate = clk_get_rate(ssc_p->ssc->clk);
 
-	/* Reset the SSC to keep it at a clean status */
-	ssc_writel(ssc_p->ssc->regs, CR, SSC_BIT(CR_SWRST));
+	/* Reset the SSC if it is not initialized to keep it at a clean status */
+	if(!ssc_p->initialized)
+		ssc_writel(ssc_p->ssc->regs, CR, SSC_BIT(CR_SWRST));
 
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		dir = 0;
-- 
2.1.4