diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.4/0141-Limit-PCM512x-Digital-gain-to-0dB-by-default-with-Hi.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.4/0141-Limit-PCM512x-Digital-gain-to-0dB-by-default-with-Hi.patch | 98 |
1 files changed, 98 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.4/0141-Limit-PCM512x-Digital-gain-to-0dB-by-default-with-Hi.patch b/target/linux/brcm2708/patches-4.4/0141-Limit-PCM512x-Digital-gain-to-0dB-by-default-with-Hi.patch new file mode 100644 index 0000000..cc28de8 --- /dev/null +++ b/target/linux/brcm2708/patches-4.4/0141-Limit-PCM512x-Digital-gain-to-0dB-by-default-with-Hi.patch @@ -0,0 +1,98 @@ +From 6fda328fc5613d449641ad6701fe8180e70ec338 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 141/232] 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); |