[alsa-devel] [PATCH] ASoC: sgtl5000: add delay before first I2C access

[Eric Nelson]

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

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

Signed-off-by: Eric Nelson <eric.nelson at boundarydevices.com>
---
 sound/soc/codecs/sgtl5000.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/sound/soc/codecs/sgtl5000.c b/sound/soc/codecs/sgtl5000.c
index 29cf7ce..7d65a5b 100644
--- a/sound/soc/codecs/sgtl5000.c
+++ b/sound/soc/codecs/sgtl5000.c
@@ -1462,6 +1462,9 @@ static int sgtl5000_i2c_probe(struct i2c_client *client,
 	if (ret)
 		return ret;
 
+	/* Need 8 clocks before I2C accesses */
+	usleep_range(1, 2);
+
 	/* read chip information */
 	ret = regmap_read(sgtl5000->regmap, SGTL5000_CHIP_ID, &reg);
 	if (ret)
-- 
1.9.1