ALSA: ASoC: cs4271: add optional soft reset workaround
The CS4271 requires its LRCLK and MCLK to be stable before its RESET
line is de-asserted. That also means that clocks cannot be changed
without putting the chip back into hardware reset, which also requires
a complete re-initialization of all registers.
One (undocumented) workaround is to assert and de-assert the PDN bit
in the MODE2 register.
This patch adds a new flag to both the DT bindings as well as to the
platform data to enable that workaround.
Signed-off-by: Daniel Mack <zonque@gmail.com>
Acked-by: Alexander Sverdlin <subaparts@yandex.ru>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
diff --git a/sound/soc/codecs/cs4271.c b/sound/soc/codecs/cs4271.c
index ac8742a..2415a41 100644
--- a/sound/soc/codecs/cs4271.c
+++ b/sound/soc/codecs/cs4271.c
@@ -167,6 +167,8 @@
int gpio_nreset;
/* GPIO that disable serial bus, if any */
int gpio_disable;
+ /* enable soft reset workaround */
+ bool enable_soft_reset;
};
/*
@@ -325,6 +327,33 @@
int i, ret;
unsigned int ratio, val;
+ if (cs4271->enable_soft_reset) {
+ /*
+ * Put the codec in soft reset and back again in case it's not
+ * currently streaming data. This way of bringing the codec in
+ * sync to the current clocks is not explicitly documented in
+ * the data sheet, but it seems to work fine, and in contrast
+ * to a read hardware reset, we don't have to sync back all
+ * registers every time.
+ */
+
+ if ((substream->stream == SNDRV_PCM_STREAM_PLAYBACK &&
+ !dai->capture_active) ||
+ (substream->stream == SNDRV_PCM_STREAM_CAPTURE &&
+ !dai->playback_active)) {
+ ret = snd_soc_update_bits(codec, CS4271_MODE2,
+ CS4271_MODE2_PDN,
+ CS4271_MODE2_PDN);
+ if (ret < 0)
+ return ret;
+
+ ret = snd_soc_update_bits(codec, CS4271_MODE2,
+ CS4271_MODE2_PDN, 0);
+ if (ret < 0)
+ return ret;
+ }
+ }
+
cs4271->rate = params_rate(params);
/* Configure DAC */
@@ -484,6 +513,10 @@
if (of_get_property(codec->dev->of_node,
"cirrus,amutec-eq-bmutec", NULL))
amutec_eq_bmutec = true;
+
+ if (of_get_property(codec->dev->of_node,
+ "cirrus,enable-soft-reset", NULL))
+ cs4271->enable_soft_reset = true;
}
#endif
@@ -492,6 +525,7 @@
gpio_nreset = cs4271plat->gpio_nreset;
amutec_eq_bmutec = cs4271plat->amutec_eq_bmutec;
+ cs4271->enable_soft_reset = cs4271plat->enable_soft_reset;
}
if (gpio_nreset >= 0)