currently we are trying to make some serial transactions with UART 3 and 4. We are using both Colibri VF50 and VF61 for tests with the same outcome. BSP is Colibri_VF_LinuxImageV2.5 with a custom DTB.
We’ve followed your Vybrid based device tree customization tutorial (http://developer.toradex.com/device-tree-customization#Vybrid_based_Modules) in order to create another DTB with UART3 and 4 with status = okay (I shall leave the dts and dtb attached).
Just for a quick test, only DTBs are updated, kernel is left untouched. NAND flashed from SD and /dev/ttyLP3 and /dev/ttyLP4 correctly appear after booting (TFT doesn’t work and before login I’m having a info message of task blocked repeating itself every 10 seconds - these are not the issue, for now).
Checking Colibri Datasheet, the only reference that I find regarding UART3 and 4 pinout are SODIMM 29/31 for UART3_RX, SODIMM 23/37 for UART3_TX, SODIMM 53 for UART4_RX amd SODIMM 51 for UART4_TX. After getting the ports stty’d , I’m trying to get some data transmitted (echo “foobar” > /dev/ttyLP2) or recieved (cat /dev/ttyLP2) through these pins, but no data is received nor transmitted.
My guess is that maybe I’m missing some pinmux set for those UART but I couldn’t find any more info saying that in the tutorials, although checking vf-colibri.dtsi I find some interesting fields that seem to set the uart0, uart1 and uart2 pins through pinctrl_uart0, pinctrl_uart1 and pinctrl_uart2, respectively.