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ASoC: sgtl5000: Allow LRCLK pad drive strength to be changed 

Introduce the "lrclk-strength" property to allow LRCLK pad drive strength
to be changed via device tree.

When running a stress playback loop test on a mx6dl wandboard channel
swap can be noticed on about 10% of the times.

While debugging this issue I noticed that when probing the SGTL5000
LRCLK pin with the scope the swap did not happen. After removing
the probe the swap started to happen again.

After changing the LRCLK pad drive strength to the maximum value the
issue is gone.

Same fix works on a mx6dl Colibri board as well.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
Tested-by: Max Krummenacher <max.krummenacher@toradex.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Fabio Estevam 2017-04-05 11:32:34 -03:00 committed by Mark Brown
parent a5de5b74a5
commit 570c70a60f
2 changed files with 27 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
Documentation/devicetree/bindings/sound/sgtl5000.txt
View File

@ -26,6 +26,15 @@ Optional properties:
If this node is not mentioned or the value is unknown, then
the value is set to 1.25V.
- lrclk-strength: the LRCLK pad strength. Possible values are:
0, 1, 2 and 3 as per the table below:
VDDIO 1.8V 2.5V 3.3V
0 = Disable
1 = 1.66 mA 2.87 mA 4.02 mA
2 = 3.33 mA 5.74 mA 8.03 mA
3 = 4.99 mA 8.61 mA 12.05 mA
Example:
codec: sgtl5000@0a {

19
sound/soc/codecs/sgtl5000.c
View File

@ -99,6 +99,13 @@ enum sgtl5000_micbias_resistor {
SGTL5000_MICBIAS_8K = 8,
};
enum {
I2S_LRCLK_STRENGTH_DISABLE,
I2S_LRCLK_STRENGTH_LOW,
I2S_LRCLK_STRENGTH_MEDIUM,
I2S_LRCLK_STRENGTH_HIGH,
};
/* sgtl5000 private structure in codec */
struct sgtl5000_priv {
int sysclk; /* sysclk rate */
@ -111,6 +118,7 @@ struct sgtl5000_priv {
int revision;
u8 micbias_resistor;
u8 micbias_voltage;
u8 lrclk_strength;
};
/*
@ -1089,6 +1097,7 @@ static int sgtl5000_enable_regulators(struct i2c_client *client)
static int sgtl5000_probe(struct snd_soc_codec *codec)
{
int ret;
u16 reg;
struct sgtl5000_priv *sgtl5000 = snd_soc_codec_get_drvdata(codec);
/* power up sgtl5000 */
@ -1118,7 +1127,8 @@ static int sgtl5000_probe(struct snd_soc_codec *codec)
SGTL5000_DAC_MUTE_RIGHT |
SGTL5000_DAC_MUTE_LEFT);
snd_soc_write(codec, SGTL5000_CHIP_PAD_STRENGTH, 0x015f);
reg = ((sgtl5000->lrclk_strength) << SGTL5000_PAD_I2S_LRCLK_SHIFT | 0x5f);
snd_soc_write(codec, SGTL5000_CHIP_PAD_STRENGTH, reg);
snd_soc_write(codec, SGTL5000_CHIP_ANA_CTRL,
SGTL5000_HP_ZCD_EN |
@ -1347,6 +1357,13 @@ static int sgtl5000_i2c_probe(struct i2c_client *client,
}
}
sgtl5000->lrclk_strength = I2S_LRCLK_STRENGTH_LOW;
if (!of_property_read_u32(np, "lrclk-strength", &value)) {
if (value > I2S_LRCLK_STRENGTH_HIGH)
value = I2S_LRCLK_STRENGTH_LOW;
sgtl5000->lrclk_strength = value;
}
/* Ensure sgtl5000 will start with sane register values */
sgtl5000_fill_defaults(client);