From: Peter Seiderer <ps.report@gmx.net>
To: linux-kernel@vger.kernel.org
Cc: Liam Girdwood <lgirdwood@gmail.com>,
Mark Brown <broonie@kernel.org>, Jaroslav Kysela <perex@perex.cz>,
Takashi Iwai <tiwai@suse.com>, b-ak <anur.bhargav@gmail.com>,
Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>,
alsa-devel@alsa-project.org
Subject: [RFC v1] tlv320aic32x4: delay i2c access by 1 ms after hardware reset
Date: Sun, 10 Feb 2019 16:45:19 +0100 [thread overview]
Message-ID: <20190210154519.2506-1-ps.report@gmx.net> (raw)
As stated in 'TLV320AIC3254 Application Reference Guide' ([1]):
3.2 Device Startup Lockout Times
After the TLV320AIC3254 initializes through hardware reset at power-up
or software reset, the internal registers initialize to default values.
This initialization takes place within 1ms after pulling the RESET
signal high. During this initialization phase, no register-read or
register-write operation should be performed on ADC or DAC coefficient
buffers. Also, no block within the codec should be powered up during
the initialization phase.
[1] http://www.ti.com/lit/an/slaa408a/slaa408a.pdf
Signed-off-by: Peter Seiderer <ps.report@gmx.net>
---
Note: This came up after the electronic departement took a deeper look at
the i2c-bus/vcc/reset pins with a logic analyzer and the documentation
because of a vcc/reset timing problem (now fixed on custom board).
Not 100% sure if the 1 ms is needed (as restricted to ADC/DAC coefficent
and codec block power up).
---
sound/soc/codecs/tlv320aic32x4.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/sound/soc/codecs/tlv320aic32x4.c b/sound/soc/codecs/tlv320aic32x4.c
index e1bfba62fc08..b3beb0ca87c3 100644
--- a/sound/soc/codecs/tlv320aic32x4.c
+++ b/sound/soc/codecs/tlv320aic32x4.c
@@ -972,6 +972,8 @@ static int aic32x4_component_probe(struct snd_soc_component *component)
gpio_set_value(aic32x4->rstn_gpio, 1);
}
+ mdelay(1);
+
snd_soc_component_write(component, AIC32X4_RESET, 0x01);
if (aic32x4->setup)
--
2.20.1
next reply other threads:[~2019-02-10 15:46 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-10 15:45 Peter Seiderer [this message]
2019-02-11 15:04 ` [RFC v1] tlv320aic32x4: delay i2c access by 1 ms after hardware reset Mark Brown
2019-02-11 21:02 ` Peter Seiderer
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