linux-kernel - [PATCH 3.18 32/39] ASoC: sgtl5000: add delay before first I2C access

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Date:	Mon,  9 Feb 2015 16:34:15 +0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org,
	Eric Nelson <eric.nelson@...ndarydevices.com>,
	Fabio Estevam <fabio.estevam@...escale.com>,
	Mark Brown <broonie@...nel.org>
Subject: [PATCH 3.18 32/39] ASoC: sgtl5000: add delay before first I2C access

3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric Nelson <eric.nelson@...ndarydevices.com>

commit 58cc9c9a175885bbf6bae3acf18233d0a8229a84 upstream.

To quote from section 1.3.1 of the data sheet:
	The SGTL5000 has an internal reset that is deasserted
	8 SYS_MCLK cycles after all power rails have been brought
	up. After this time, communication can start

	...
	1.0us represents 8 SYS_MCLK cycles at the minimum 8.0 MHz SYS_MCLK.

Signed-off-by: Eric Nelson <eric.nelson@...ndarydevices.com>
Reviewed-by: Fabio Estevam <fabio.estevam@...escale.com>
Signed-off-by: Mark Brown <broonie@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 sound/soc/codecs/sgtl5000.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/sound/soc/codecs/sgtl5000.c
+++ b/sound/soc/codecs/sgtl5000.c
@@ -1452,6 +1452,9 @@ static int sgtl5000_i2c_probe(struct i2c
 	if (ret)
 		return ret;
 
+	/* Need 8 clocks before I2C accesses */
+	udelay(1);
+
 	/* read chip information */
 	ret = regmap_read(sgtl5000->regmap, SGTL5000_CHIP_ID, &reg);
 	if (ret)


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