topic Re: IMX7D IO multiplexing in i.MX Processors

IMX7D IO multiplexing

864535720 — Fri, 12 Apr 2019 01:10:02 GMT

Hello everyone
The chip model I am using is MCIMX7D7DVM10SD. We refer to the official website of the official website MCIMX7SABRE development board. We are using the eMMC approach. Therefore, we want to use the SD1_CLK pin as a normal GPIO port. But we are multiplexing this IO port and using it as an output. But when we measure this IO port, we get a low level. Below is our code. Is there any problem with our configuration?

    ssd2828{
       compatible = "comen,ssd2828";
       pinctrl-names = "default";
       pintctrl-0 = <&pinctrl_ssd2828>;
       status = "okay";
       gpio-mosi = <&gpio5 0 0>;
       gpio-miso = <&gpio5 1 0>;
       gpio-sclk = <&gpio5 2 0>;
        gpio-cs = <&gpio5 3 0>;                   //fail
       ssd2828-reset = <&gpio3 4 1>;
   };

pinctrl_ssd2828:spi-ssd2828{
       fsl,pins = <
                   MX7D_PAD_SD1_CLK__GPIO5_IO3 0x37      //fail
//                   MX7D_PAD_SD1_CLK__GPIO5_IO3 0x59      //fail
//                   MX7D_PAD_SD1_CLK__GPIO5_IO3 0x18      //fail
//                   MX7D_PAD_SD1_CLK__GPIO5_IO3 0x1b      //fail
               >;
       };

ssd2828_info_data->spi_cs = of_get_named_gpio(node, "gpio-cs", 0); //success

ret = gpio_request(ssd2828_info_data->spi_cs, "cs"); //success

ret = gpio_direction_output(ssd2828_info_data->spi_cs, 1); //success， but Measurement level is 0

We are using GPIO5-IO3, this pin has not been able to work as we expected, its level has been 0

I hope everyone can help.

Re: IMX7D IO multiplexing

igorpadykov — Fri, 12 Apr 2019 05:18:49 GMT

Hi 其东刘

this pin is used in pinctrl_usdhc1: usdhc1grp in

linux/arch/arm/boot/dts/imx7d-sdb.dts

imx7d-sdb.dts\dts\boot\arm\arch - linux-imx - i.MX Linux kernel

so one can try to disable usdhc1: status = "okay";

Also one can attach jtag debugger and check iomux registers for that pin.

Best regards
igor
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Re: IMX7D IO multiplexing

864535720 — Sun, 14 Apr 2019 04:54:34 GMT

Hi igorpadykov

I changed the status to status = "disabled" according to what you said.
Then I checked my GPIO5-IO3 usage again and determined that it was not used elsewhere.
At the same time I also tried another way.
Cd /sys/class/gpio
Echo 131 > export
Cd gpio131
Echo out > direction
Echo 1 > value
Echo 0 > value

During the above command execution, no error message is prompted. But when I went to detect the level status of GPIO-IO3, I found that it was always 0.
May I ask me what is the solution to this situation? Or you can test on your board to see if this can be resolved.
look forward to your reply

Re: IMX7D IO multiplexing

igorpadykov — Sun, 14 Apr 2019 22:42:34 GMT

to check if linux seetings become valid one can attach jtag debugger and

look at iomux registers for that pin, then try to toggle pin using jtag to check if pin

is not shorted on board or damaged.

Best regards
igor