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Allow up to 24dB digital gain to be applied when using IQAudIO DAC

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24db_digital_gain DT param can be used to specify that PCM512x
codec "Digital" volume control should not be limited to 0dB gain,
and if specified will allow the full 24dB gain.

Signed-off-by: DigitalDreamtime <clive.messer@digitaldreamtime.co.uk>
This commit is contained in:
DigitalDreamtime
2016-05-06 09:42:55 +01:00
parent 9083d49e21
commit 7f84c3af0b
2 changed files with 20 additions and 3 deletions
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17
arch/arm/boot/dts/overlays/README
View File

@@ -490,8 +490,21 @@ Params: <None>
Name: iqaudio-dac
Info: Configures the IQaudio DAC audio card
Load: dtoverlay=iqaudio-dac
Params: <None>
Load: dtoverlay=iqaudio-dac,<param>
Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
Digital volume control. Enable with
"dtoverlay=iqaudio-dac,24db_digital_gain"
(The default behaviour is that the Digital
volume control is limited to a maximum of
0dB. ie. it can attenuate but not provide
gain. For most users, this will be desired
as it will prevent clipping. By appending
the 24db_digital_gain parameter, the Digital
volume control will allow up to 24dB of
gain. If this parameter is enabled, it is the
responsibility of the user to ensure that
the Digital volume control is set to a value
that does not result in clipping/distortion!)
Name: iqaudio-dacplus

6
arch/arm/boot/dts/overlays/iqaudio-dac-overlay.dts
View File

@@ -30,10 +30,14 @@
fragment@2 {
target = <&sound>;
__overlay__ {
frag2: __overlay__ {
compatible = "iqaudio,iqaudio-dac";
i2s-controller = <&i2s>;
status = "okay";
};
};
__overrides__ {
24db_digital_gain = <&frag2>,"iqaudio,24db_digital_gain?";
};
};