IMX8mini EVK Using UART2 directly

[baptiste]

Hi,

I use an IMX8MINI EVK Board with an Azur SOM.
I want to use UART2 directly in Linux.
As far as i understand, i have soldered two wires in TP905 (TX2) and TP906 (RX2).
For now,  i have strapped the two wires to test, but it does not work.

I have read than A53 debug goes to Uart2. How to disable that ? I have also disabled DMA on uart2 and my dmesg console looks like that :

[ 0.148499] 30860000.serial: ttymxc0 at MMIO 0x30860000 (irq = 41, base_baud = 5000000) is a IMX
[ 0.149107] 30880000.serial: ttymxc2 at MMIO 0x30880000 (irq = 42, base_baud = 5000000) is a IMX
[ 0.149607] 30890000.serial: ttymxc1 at MMIO 0x30890000 (irq = 43, base_baud = 1500000) is a IMX

What should i do ?

For example, i try with a raspberry pi 4 and it is OK on GPIO 8-10.

Best regards,
Baptiste

[baptiste]

Hi Jimmychan,
Thanks for your quick reply. I have modified dts, unsucessfully.
It does not matter, i am working on SPI side now instead of UART.
I would like to use SPI2 which is on J1003 connector of IMX8MMEVK-BOARD.

I have found some examples of dts file, but i did not undestand this :

In the IMX 8M Processor Reference manual, i read this (i need ALT0 MUX MODE for ECSPI2_MOSI)
Where is this definition ? in DTS file ?
IOMUXC_SW_MUX_CTL_PAD_ECSPI2_MODI = bits 31-5 reserved, 4 SION, 3 reserved, MUX-MODE 1-3(Alt0 = 000)
So the value shoud be, with bit 4 set to 1 : 000000000 000000000 000000000 00010000 = 0x00000010, am i right ?

I some examples, i see :

+ pinctrl_ecspi2: ecspi2grp {
+ fsl,pins = <
+ MX8MM_IOMUXC_ECSPI2_SCLK_ECSPI2_SCLK 0x82
+ MX8MM_IOMUXC_ECSPI2_MOSI_ECSPI2_MOSI 0x82
+ MX8MM_IOMUXC_ECSPI2_MISO_ECSPI2_MISO 0x82
+ >;
+ };
+
+ pinctrl_ecspi2_cs: ecspi2cs {
+ fsl,pins = <
+ MX8MM_IOMUXC_ECSPI2_SS0_GPIO5_IO13 0x40000
+ >;
+ };
+

What is the 0x82 ?

Best regards,

Baptiste

[jimmychan]

The pinmux definition of each pin can be found in the imx8mm-pinfunc.h.

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8mm-pinfu...

0x82 is the value for PAD control register. (setting for PE, HYS, PUS, ODE, FSEL and DSE)

for example : please read the chapter 8.2.5.280 Pad Control Register (IOMUXC_SW_PAD_CTL_PAD_ECSPI2_MOSI) in the i.MX8MM RM.

[jimmychan]

There is device tree file. Have you try to modify it?

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8mm-evk.d...