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 --- Documentation/devicetree/bindings/sound/sgtl5000.txt | 9 +++++++++ sound/soc/codecs/sgtl5000.c | 19 ++++++++++++++++++- 2 files changed, 27 insertions(+), 1 deletion(-)
diff --git a/Documentation/devicetree/bindings/sound/sgtl5000.txt b/Documentation/devicetree/bindings/sound/sgtl5000.txt index 5666da7..7a73a9d 100644 --- a/Documentation/devicetree/bindings/sound/sgtl5000.txt +++ b/Documentation/devicetree/bindings/sound/sgtl5000.txt @@ -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 { diff --git a/sound/soc/codecs/sgtl5000.c b/sound/soc/codecs/sgtl5000.c index 1589325..5a2702e 100644 --- a/sound/soc/codecs/sgtl5000.c +++ b/sound/soc/codecs/sgtl5000.c @@ -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);