[rk3288][Android7.1]系统重启后speaker杂音问题

问题描述

• 通过adb重启设备会出现杂音，全频段的杂音
• 正常重启也会出现
• 系统启动后如果播放任意一段音频后杂音消失
• 系统关机后重新开机或者pmic reset后开机均没有此现象

问题分析

• 首先怀疑codec的配置问题，由于android7.1属于系统升级，在android5.1中没有这个现象，对比kernel中的配置完全一样
• 通过示波器测量codec i2c 控制信号，以及i2s的数据信号，确定speaker的信号源就是来自i2s
• 进一步对比两套代码在i2s的配置发现，android5.1中在codec suspend时会将i2s的gpio配置为普通gpio

解决方法

至此找到问题的root cause，解决方法就是在suspend时将i2s配置为普通gpio。

patch

diff --git a/kernel/arch/arm/boot/dts/rk3288-xxx.dtsi b/kernel/arch/arm/boot/dts/rk3288-xxx.dtsi
index 748a4ba..2c6cfc6 100644 (file)
--- a/kernel/arch/arm/boot/dts/rk3288-xxx.dtsi
+++ b/kernel/arch/arm/boot/dts/rk3288-xxx.dtsi
@@ -290,8 +290,9 @@
                reg = <0x10>;
                clocks = <&cru SCLK_I2S0_OUT>;
                clock-names = "mclk";
-               pinctrl-names = "default";
+               pinctrl-names = "default", "sleep";
                pinctrl-0 = <&i2s0_mclk>;
+               pinctrl-1 = <&i2s0_mclk_sleep>;
                #sound-dai-cells = <0>;
        };
 };

diff --git a/kernel/arch/arm/boot/dts/rk3288.dtsi b/kernel/arch/arm/boot/dts/rk3288.dtsi
index d370d67..888bc43 100644 (file)
--- a/kernel/arch/arm/boot/dts/rk3288.dtsi
+++ b/kernel/arch/arm/boot/dts/rk3288.dtsi
@@ -1173,8 +1173,9 @@
                clocks = <&cru HCLK_I2S0>, <&cru SCLK_I2S0>;
                assigned-clocks = <&cru SCLK_I2S_SRC>;
                assigned-clock-parents = <&cru PLL_GPLL>;
-               pinctrl-names = "default";
+               pinctrl-names = "default", "sleep";
                pinctrl-0 = <&i2s0_bus>;
+               pinctrl-1 = <&i2s_gpio>;
                rockchip,playback-channels = <8>;
                rockchip,capture-channels = <2>;
                status = "disabled";
@@ -2057,6 +2058,19 @@
                        i2s0_mclk: i2s0-mclk {
                                rockchip,pins = <6 8 RK_FUNC_1 &pcfg_pull_none>;
                        };
+
+                       i2s0_mclk_sleep: i2s0-mclk-sleep {
+                               rockchip,pins = <6 8 RK_FUNC_GPIO &pcfg_pull_none>;
+                       };
+
+                       i2s_gpio: i2s-gpio {
+                                       rockchip,pins = <6 0 RK_FUNC_GPIO  &pcfg_pull_none>,
+                                                       <6 1 RK_FUNC_GPIO  &pcfg_pull_none>,
+                                                       <6 2 RK_FUNC_GPIO  &pcfg_pull_none>,
+                                                       <6 3 RK_FUNC_GPIO  &pcfg_pull_none>,
+                                                       <6 4 RK_FUNC_GPIO  &pcfg_pull_none>;
+                       };
+
                };
 
                lcdc {