• State Resolved
  • Locked Locked
  • Replies 3 replies
  • Subscribers 99 subscribers
  • Views 507 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

Original question:

AM625: Cortex-R5 core (cont')

AM625: WKUP_UART0 control

Tony Tang
Mastermind 28922 points
Part Number: AM625

On customer board useWKUP_UART C5 pin as eMMC RST_n pin, which caused problem during Kernel booting up

observed signal togging on the pin with scope. so need to stop it.

Tried to disable the WKUP_UART in dts along with padconfig to gpio, but it doesn't work, readback the padconfig register MCU_PADCONFIG10 0x04084028, it still is UART0_TXD mode.

did further test, change k3-am625-r5-sk.dts as below to change wkup uart pin to gpio

boot up tiboot3.bin only over uart, then check paddonfig in CCS, it is configured to gpio.

then download tispl.bin then stop to check padconfig in CCS, only TX pin change back to UART-TX mode 0. Who modified this pin mux, and only this pin. I guess tispl wake up R5 DM firmware, firmware overwrite the pad configuration.

I found similar question here: https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1108935/am625-cortex-r5-core-cont/4126531

Stop in Uboot to change padconfig mw 0x04084028 0x08054007 to configure mcu_uart0_tx pin to gpio, then can boot up and no toggling on WKUP_UART0 anymore.

Questions:

#1. How and Where configured wkup_uart0 module and padconfigure? can it be controlled by dts? actually we tied to disable and configure the pin to gpio, but doesn't work. seems it is configured again in DM firmware

#2. Is there other pin used by DM firmware like wkup_uart0?

  • 0
    TI__Guru 69602 points

    Hi Tony! The subject owner is currently out of the office, returning tomorrow. Please allow a day or two for a response. Thanks.

  • 0
    TI__Guru**** 167581 points

    Hi Tony,

    Yes, the wkup uart is enabled by SYSFW. I am checking internally to see if it is possible to free the wkup uart for application to use.

  • +1
    TI__Guru**** 167581 points

    Hi Tony,

    I think when the U-Boot execution moves from R5 to A53, the pinmux got reset, so the wkup_uart0 pinmux goes back to mode 0. Please apply the following U-Boot patch, it will re-configure the wkup_uart0 pins to GPIO mode in A53 U-Boot.

    diff --git a/arch/arm/dts/k3-am625-sk-u-boot.dtsi b/arch/arm/dts/k3-am625-sk-u-boot.dtsi
index f2ad332f9f5d..46e3a752d891 100644
--- a/arch/arm/dts/k3-am625-sk-u-boot.dtsi
+++ b/arch/arm/dts/k3-am625-sk-u-boot.dtsi
@@ -86,6 +86,18 @@

 &mcu_pmx0 {
        u-boot,dm-spl;
+       pinctrl-names = "default";
+       pinctrl-0 = <&wkup_uart0_pins_default>;
+
+       wkup_uart0_pins_default: wkup-uart0-pins-default {
+               pinctrl-single,pins = <
+                       AM62X_MCU_IOPAD(0x02c, PIN_INPUT, 7) /* (C6) WKUP_UART0_CTSn */
+                       AM62X_MCU_IOPAD(0x030, PIN_OUTPUT, 7) /* (A4) WKUP_UART0_RTSn */
+                       AM62X_MCU_IOPAD(0x024, PIN_INPUT, 7) /* (B4) WKUP_UART0_RXD */
+                       AM62X_MCU_IOPAD(0x028, PIN_OUTPUT, 7) /* (C5) WKUP_UART0_TXD */
+               >;
+               u-boot,dm-spl;
+       };
 };

 &wkup_uart0 {