[Letux-kernel] Letux/Alpha 400: small progress with sound
H. Nikolaus Schaller
hns at goldelico.com
Sat May 1 08:51:49 CEST 2021
> Am 30.04.2021 um 00:20 schrieb Paul Boddie <paul at boddie.org.uk>:
> Yes, this is very strange. Although there are device tree nodes in the 3.18
> kernel files, I don't find the corresponding drivers. There is audio support
> in the HDMI driver, but since I use a DVI monitor, I never tried to use the
> audio on the CI20 since the cable won't be passing on any audio signal. But I
> imagine that there must be HDMI audio support because there was some effort to
> get video playback working with a special version of MPlayer, as I recall.
I have looked through the 3.18 kernel and there is an "old style sound board file":
which is compatible = "ingenic,ci20-audio"
This defines two dai links. Apparently one which is called "headphones" and one
called "hdmi". Both seem to use the jz4780-i2s. Difference is in the codecs:
dw-hdmi-audio vs. jz4780-codec.
So the hdmi audio seems to be part of a more general ci20 audio driver than
"simple-audio-card". This raises another question: should we forward port
the ci20-audio.c driver or try to make simple-audio-card work?
Anyways the codec driver can be found in sound/soc/codecs/jz4780.c
So I will replace the attempt to modify the jz4770 driver to use the one
from the 3.18 kernel...
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