RK3288 -- 關于 HDMI 音頻輸出的兩種配置

說明：本文适用于 RK3288 kernel4.4 SDK 版本。

RK3288 的 HDMI 和 codec 共用一組 i2s 。如果需要 HDMI 和 Codec 同時輸出音頻，直接使用 SDK 自帶的 hdmi_analog_sound 節點配置。如果需要 HDMI 和 codec 可以單獨輸出，需要将 HDMI 單獨注冊成一個 PCM 裝置。

注：hdmi_analog_sound 和 simple-audio-card 這兩種注冊方式隻能二選一。

HDMI 和 Codec 同時輸出

方案一：直接使用 hdmi_analog_sound 預設節點配置( 以 RT5640 為例 )

//RK3288 kernel4.4
/ {
    hdmi_analog_sound: hdmi-analog-sound {
        status = "okay";
		compatible = "rockchip,rk3288-hdmi-analog",
				"rockchip,rk3368-hdmi-analog";
		rockchip,model = "rockchip,rt5640-codec";
		rockchip,cpu = <&i2s>;
		rockchip,codec = <&rt5640>, <&hdmi>;
		rockchip,widgets =
			"Microphone", "Microphone Jack",
			"Headphone", "Headphone Jack";
		rockchip,routing =
			"MIC1", "Microphone Jack",
			"MIC2", "Microphone Jack",
			"Microphone Jack", "micbias1",
			"Headphone Jack", "HPOL",
			"Headphone Jack", "HPOR";
	};
};

&i2s {
    status = "okay";
};

&hdmi{
    status = "okay";
};

&i2c2 {
	status = "okay";
	rt5640: rt5640@1c {
		#sound-dai-cells = <0>;
		compatible = "realtek,rt5640";
		reg = <0x1c>;
		clocks = <&cru SCLK_I2S0_OUT>;
		clock-names = "mclk";
		interrupt-parent = <&gpio6>;
		interrupts = <7 IRQ_TYPE_EDGE_FALLING>;
		pinctrl-names = "default";
		pinctrl-0 = <&i2s0_mclk>;
	};
};
           

方案二：關閉上層 HDMI 裝置插入檢測，DTS 用 simple-audio-card 注冊 Codec 聲霸卡。

1、上層注釋掉 hdmi 裝置插入的檢測：

diff --git a/services/java/com/android/server/WiredAccessoryManager.java b/services/java/com/android/server/WiredAccessoryManager.java
index c8d3510..2fb231e 100644
--- a/services/java/com/android/server/WiredAccessoryManager.java
+++ b/services/java/com/android/server/WiredAccessoryManager.java
@@ -374,7 +374,7 @@ final class WiredAccessoryManager implements WiredAccessoryCallbacks {
             //
             // If the kernel does not have an "hdmi_audio" switch, just fall back on the older
             // "hdmi" switch instead.
-            uei = new UEventInfo(NAME_HDMI_AUDIO, BIT_HDMI_AUDIO, 0);
+/*            uei = new UEventInfo(NAME_HDMI_AUDIO, BIT_HDMI_AUDIO, 0);
             if (uei.checkSwitchExists()) {
                 retVal.add(uei);
             } else {
@@ -385,7 +385,7 @@ final class WiredAccessoryManager implements WiredAccessoryCallbacks {
                     Slog.w(TAG, "This kernel does not have HDMI audio support");
                 }
             }
-
+*/
             return retVal;
         }
           

2、simple-audio-card 注冊 Codec 聲霸卡

//RK3288 kernel4.4
/{
    rt5640_codec: rt5640-codec{
		status = "okay";
		compatible = "simple-audio-card";
		simple-audio-card,format = "i2s";
		simple-audio-card,name = "rockchip,rt5640-codec";
		simple-audio-card,mclk-fs = <512>;
		simple-audio-card,widgets =
			"Microphone", "Microphone Jack",
			"Headphone", "Headphone Jack";
		simple-audio-card,routing =
			"MIC1", "Microphone Jack",
			"MIC2", "Microphone Jack",
			"Microphone Jack", "micbias1",
			"Headphone Jack", "HPOL",
			"Headphone Jack", "HPOR";

		simple-audio-card,dai-link@0 {
			format = "i2s";
			cpu {
				sound-dai = <&i2s>;
			};
			codec {
				sound-dai = <&rt5640>;
			};
		};
};

&i2s {
    status = "okay";
};

&i2c2 {
	status = "okay";
	rt5640: rt5640@1c {
		#sound-dai-cells = <0>;
		compatible = "realtek,rt5640";
		reg = <0x1c>;
		clocks = <&cru SCLK_I2S0_OUT>;
		clock-names = "mclk";
		interrupt-parent = <&gpio6>;
		interrupts = <7 IRQ_TYPE_EDGE_FALLING>;
		pinctrl-names = "default";
		pinctrl-0 = <&i2s0_mclk>;
	};
};
           

HDMI 和 codec 單獨輸出

實作 HDMI 和 codec 音頻單獨輸出需要将 hdmi 單獨注冊成一個 PCM 裝置，HDMI 裝置插入後上層會切換輸出裝置為 AUDIO_DEVICE_OUT_HDMI ，然後在 HAL 層打開對應的 PCM 裝置即可。

DTS配置如下：

//RK3288 kernel4.4
/{
    rt5640_codec: rt5640-codec{
        status = "okay";
        compatible = "simple-audio-card";
        simple-audio-card,format = "i2s";
        simple-audio-card,name = "rockchip,rt5640-codec";
        simple-audio-card,mclk-fs = <512>;
        simple-audio-card,widgets =
            "Microphone", "Microphone Jack",
            "Headphone", "Headphone Jack";
        simple-audio-card,routing =
            "MIC1", "Microphone Jack",
            "MIC2", "Microphone Jack",
            "Microphone Jack", "micbias1",
            "Headphone Jack", "HPOL",
            "Headphone Jack", "HPOR";

        simple-audio-card,dai-link@0 {
            format = "i2s";
            cpu {
                sound-dai = <&i2s>;
            };
            codec {
                sound-dai = <&rt5640>;
            };
        };
        simple-audio-card,dai-link@1 {
            format = "i2s";
            cpu {
                sound-dai = <&i2s>;
            };
            codec {
                sound-dai = <&hdmi>;
            };
        };
    };
};

&hdmi_analog_sound {
    status = "disabled";
};

&i2s {
    status = "okay";
};

&i2c2 {
	status = "okay";
	rt5640: rt5640@1c {
		#sound-dai-cells = <0>;
		compatible = "realtek,rt5640";
		reg = <0x1c>;
		clocks = <&cru SCLK_I2S0_OUT>;
		clock-names = "mclk";
		interrupt-parent = <&gpio6>;
		interrupts = <7 IRQ_TYPE_EDGE_FALLING>;
		pinctrl-names = "default";
		pinctrl-0 = <&i2s0_mclk>;
	};
};
           

注冊成功後，可以通過 adb 檢視注冊上的 pcm裝置。

rk3228:/ # ls dev/snd
ls dev/snd
. .. controlC0 pcmC0D0c pcmC0D0p pcmC0D1p timer
           

其中 pcmC0D1p 對應的就是 HDMI pcm 裝置，然後在 hal 層調用 pcmC0D1p ，修改如下：

hardware/rockchip/audio/tinyalsa_hal$ git diff .
diff --git a/tinyalsa_hal/audio_hw.c b/tinyalsa_hal/audio_hw.c
index 13dd42e..fd7c664 100755
--- a/tinyalsa_hal/audio_hw.c
+++ b/tinyalsa_hal/audio_hw.c
@@ -615,7 +615,7 @@ static int start_output_stream(struct stream_out *out)
             }
 #endif
 #endif
-            out->pcm[PCM_CARD_HDMI] = pcm_open(PCM_CARD_HDMI, out->pcm_device,
+            out->pcm[PCM_CARD_HDMI] = pcm_open(0, 1,
                                                 PCM_OUT | PCM_MONOTONIC, &out->config);
             if (out->pcm[PCM_CARD_HDMI] &&
                     !pcm_is_ready(out->pcm[PCM_CARD_HDMI])) {
              
           

注：具體 hdmi 對應的是哪個 pcm 裝置需要根據實際情況來定，如果不清楚怎麼确認，底層可以先通過 tinyalsa 來确定 hdmi 的 pcm 裝置，然後參照上述 hal 層的代碼修改成對應的 hdmi pcm 裝置 即可。