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