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

From: Greg Kroah-Hartman
Date: Mon Feb 09 2015 - 03:45:50 EST

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


From: Eric Nelson <eric.nelson@xxxxxxxxxxxxxxxxxxx>

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@xxxxxxxxxxxxxxxxxxx>
Reviewed-by: Fabio Estevam <fabio.estevam@xxxxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

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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