61 lines
2.4 KiB
Diff
61 lines
2.4 KiB
Diff
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From ba4e2749004660d573c0d62f6fec876cd152bd3e Mon Sep 17 00:00:00 2001
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From: DigitalDreamtime <clive.messer@digitaldreamtime.co.uk>
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Date: Fri, 6 May 2016 09:42:55 +0100
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Subject: [PATCH 327/381] Allow up to 24dB digital gain to be applied when
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using IQAudIO DAC
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24db_digital_gain DT param can be used to specify that PCM512x
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codec "Digital" volume control should not be limited to 0dB gain,
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and if specified will allow the full 24dB gain.
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Signed-off-by: DigitalDreamtime <clive.messer@digitaldreamtime.co.uk>
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---
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arch/arm/boot/dts/overlays/README | 17 +++++++++++++++--
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arch/arm/boot/dts/overlays/iqaudio-dac-overlay.dts | 6 +++++-
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2 files changed, 20 insertions(+), 3 deletions(-)
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--- a/arch/arm/boot/dts/overlays/README
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+++ b/arch/arm/boot/dts/overlays/README
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@@ -490,8 +490,21 @@ Params: <None>
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Name: iqaudio-dac
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Info: Configures the IQaudio DAC audio card
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-Load: dtoverlay=iqaudio-dac
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-Params: <None>
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+Load: dtoverlay=iqaudio-dac,<param>
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+Params: 24db_digital_gain Allow gain to be applied via the PCM512x codec
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+ Digital volume control. Enable with
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+ "dtoverlay=iqaudio-dac,24db_digital_gain"
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+ (The default behaviour is that the Digital
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+ volume control is limited to a maximum of
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+ 0dB. ie. it can attenuate but not provide
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+ gain. For most users, this will be desired
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+ as it will prevent clipping. By appending
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+ the 24db_digital_gain parameter, the Digital
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+ volume control will allow up to 24dB of
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+ gain. If this parameter is enabled, it is the
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+ responsibility of the user to ensure that
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+ the Digital volume control is set to a value
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+ that does not result in clipping/distortion!)
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Name: iqaudio-dacplus
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--- a/arch/arm/boot/dts/overlays/iqaudio-dac-overlay.dts
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+++ b/arch/arm/boot/dts/overlays/iqaudio-dac-overlay.dts
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@@ -30,10 +30,14 @@
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fragment@2 {
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target = <&sound>;
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- __overlay__ {
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+ frag2: __overlay__ {
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compatible = "iqaudio,iqaudio-dac";
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i2s-controller = <&i2s>;
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status = "okay";
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};
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};
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+
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+ __overrides__ {
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+ 24db_digital_gain = <&frag2>,"iqaudio,24db_digital_gain?";
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+ };
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};
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