99 lines
3.6 KiB
Diff
99 lines
3.6 KiB
Diff
From 5eb11c1a6735ddbcb4b37014caf5945123aad8a2 Mon Sep 17 00:00:00 2001
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From: Digital Dreamtime <clive.messer@digitaldreamtime.co.uk>
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Date: Thu, 4 Feb 2016 20:04:00 +0000
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Subject: [PATCH] Limit PCM512x "Digital" gain to 0dB by default with HiFiBerry
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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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---
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arch/arm/boot/dts/overlays/README | 17 +++++++++++++++--
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.../arm/boot/dts/overlays/hifiberry-dacplus-overlay.dts | 6 +++++-
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sound/soc/bcm/hifiberry_dacplus.c | 14 ++++++++++++++
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3 files changed, 34 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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@@ -273,8 +273,21 @@ Params: <None>
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Name: hifiberry-dacplus
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Info: Configures the HifiBerry DAC+ audio card
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-Load: dtoverlay=hifiberry-dacplus
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-Params: <None>
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+Load: dtoverlay=hifiberry-dacplus,<param>=<val>
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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=hifiberry-dacplus,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: hifiberry-digi
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--- a/arch/arm/boot/dts/overlays/hifiberry-dacplus-overlay.dts
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+++ b/arch/arm/boot/dts/overlays/hifiberry-dacplus-overlay.dts
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@@ -17,7 +17,7 @@
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fragment@1 {
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target = <&sound>;
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- __overlay__ {
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+ frag1: __overlay__ {
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compatible = "hifiberry,hifiberry-dacplus";
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i2s-controller = <&i2s>;
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status = "okay";
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@@ -47,4 +47,8 @@
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};
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};
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};
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+
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+ __overrides__ {
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+ 24db_digital_gain = <&frag1>,"hifiberry,24db_digital_gain?";
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+ };
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};
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--- a/sound/soc/bcm/hifiberry_dacplus.c
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+++ b/sound/soc/bcm/hifiberry_dacplus.c
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@@ -48,6 +48,7 @@ struct pcm512x_priv {
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#define CLK_48EN_RATE 24576000UL
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static bool snd_rpi_hifiberry_is_dacpro;
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+static bool digital_gain_0db_limit = true;
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static void snd_rpi_hifiberry_dacplus_select_clk(struct snd_soc_codec *codec,
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int clk_id)
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@@ -167,6 +168,16 @@ static int snd_rpi_hifiberry_dacplus_ini
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snd_soc_update_bits(codec, PCM512x_GPIO_OUTPUT_4, 0x0f, 0x02);
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snd_soc_update_bits(codec, PCM512x_GPIO_CONTROL_1, 0x08, 0x08);
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+ if (digital_gain_0db_limit)
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+ {
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+ int ret;
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+ struct snd_soc_card *card = rtd->card;
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+
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+ ret = snd_soc_limit_volume(card, "Digital Playback Volume", 207);
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+ if (ret < 0)
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+ dev_warn(card->dev, "Failed to set volume limit: %d\n", ret);
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+ }
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+
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return 0;
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}
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@@ -299,6 +310,9 @@ static int snd_rpi_hifiberry_dacplus_pro
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dai->platform_name = NULL;
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dai->platform_of_node = i2s_node;
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}
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+
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+ digital_gain_0db_limit = !of_property_read_bool(
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+ pdev->dev.of_node, "hifiberry,24db_digital_gain");
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}
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ret = snd_soc_register_card(&snd_rpi_hifiberry_dacplus);
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