y97788 发布的最佳帖子

@whycan 将设备树这三行注释掉就好了，

  twi_drv_used = <1>;
 dmas = <&dma 45>, <&dma 45>;
 dma-names = "tx", "rx";

T113S使用i2c接口连接外置RTC初始化失败，这个是什么原因

[    4.429716] sunxi-i2c sunxi-i2c2: sunxi-i2c2 supply twi not found, using dummy regulator
 [    4.444395] sunxi-i2c sunxi-i2c2: drv-mode: Timeout when sending 9th SCL clk
[    4.452364] sunxi-i2c sunxi-i2c2: drv-mode: xfer failed (dev addr:0x51)
[    4.459795] rtc-pcf8563 2-0051: pcf8563_write_block_data: err=-22 addr=0e, data=03
[    4.468327] rtc-pcf8563 2-0051: pcf8563_probe: write error
[    4.474816] rtc-pcf8563: probe of 2-0051 failed with error -5
[    4.481305] sunxi-i2c sunxi-i2c2: probe success
[    4.488591] sunxi-i2c sunxi-i2c3: sunxi-i2c3 supply twi not found, using dummy regulator
[    4.501228] sunxi-i2c sunxi-i2c3: probe success

使用longanLinux kernel5.4设备树配置

 twi2_pins_a: twi2@0 {
 	pins = "PG14", "PG15";
 	function = "twi2";
 	drive-strength = <10>;
 };

 twi2_pins_b: twi2@1 {
 	pins = "PG14", "PG15";
 	function = "gpio_in";
 };

 &twi2 {
 clock-frequency = <400000>;
 pinctrl-0 = <&twi2_pins_a>;
 pinctrl-1 = <&twi2_pins_b>;
 pinctrl-names = "default", "sleep";
 twi_drv_used = <1>;
 dmas = <&dma 45>, <&dma 45>;
 dma-names = "tx", "rx";
 status = "okay";
 pcf8563: pcf8563@51 {
 	compatible = "nxp,pcf8563";
 	reg = <0x51>;
 	#clock-cells = <0>;
 };

};