how to enable uart4

[mingmingyuan]

we use mx6q sabresd board and run linux 3.0.35, now I want to use uart4,but I can't find ttymxc3 in /dev/

I read porting guide for this, I add follow code in board.c, after add this code, I can find ttymxc3 in /dev, but this uart can't send or receive data.

	// yuanmm add uart begin
	imx6q_add_imx_uart(1, NULL);
	imx6q_add_imx_uart(3, NULL);
	imx6q_add_imx_uart(4, NULL);
	// yuanmm add uart end

test step:

cat /dev/ttymxc3 &

echo ymm > /dev/ttymxc3

[saurabh206]

Hi

Please check the UART setting (e.g. DMA enable, flow control setting) in the linux/arch/arm/mach-mx6/serial.h.

Thanks

Saurabh

[mingmingyuan]

I don't modify other code after I got bsp code , as your mean, bsp code can't support uart when use default setting( e.g DMA and flow control)

[saurabh206]

Hi

It may possible that UART4 is not used so it might be disabled, so it better to verify.

It should be like

#define UART4_UCR4_CTSTL        16

#define UART4_DMA_ENABLE 1

#define UART4_DMA_RXBUFSIZE    512

#define UART4_UFCR_RXTL        16

#define UART4_UFCR_TXTL        16

Thanks

Saurabh

[mingmingyuan]

OK, thank you for your help, I think your suggestion is right.

I will check this.

[mingmingyuan]

I have modified code, but uart4 can't work still.

/* UART 4 configuration */

#define UART4_UCR4_CTSTL        16// yuanmm change to 16 before is -1

#define UART4_DMA_ENABLE 1// yuanmm change to 1 before is 0

#define UART4_DMA_RXBUFSIZE     512// this number I have tried 512 and 1024

#define UART4_UFCR_RXTL         16

#define UART4_UFCR_TXTL         16

[mingmingyuan]

hi fsl：

any update？

[Rita_Wang]

Hi mingming yuan,

Here I have a document for Debug UART Customization on i.MX6x. There are steps about how to modify you can refer to .

In the attachment you can see the document. Hope this can help you.
Have a great day
Dan

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

[mingmingyuan]

Hi DanWang：

thank you for provide me document，I will read this doc and respond as soon as  possiable.

[mingmingyuan]

Hi danwang:

thank you for your support.

I have read this ppt and modified code for test, but uart4 can't work still.

this is my step, can you help to double check?

I want to use uart4 for data transmit in kernel not for debug, So I think I only need to modify code in kernel, needn't modify uboot and MFT code.

ppt description for board-mx6q_arm2, but I use sabresd board, so I need to modify Board-mx6q_sabresd.c and releational file.

1,arch\arm\mach-mx6\serial.h

I check uart4 configration and only change UART4_UCR4_CTSTL from -1 to 16, other configration use default setting

/* UART 4 configuration */

#define UART4_UCR4_CTSTL        16// yuanmm change to 16 before is -1

#define UART4_DMA_ENABLE 0

#define UART4_DMA_RXBUFSIZE     512

#define UART4_UFCR_RXTL         16

#define UART4_UFCR_TXTL         16

2, arch\arm\mach-mx6\Board-mx6q_sabresd.h

add code as follow,as hareware design, We use pad csi0 data12 and data13,not PAD_KEY_COL0

  // yuanmm add begin

  MX6Q_PAD_CSI0_DAT12__UART4_TXD,

  MX6Q_PAD_CSI0_DAT13__UART4_RXD,

  // yuanmm add end

3, arch\arm\mach-mx6\Board-mx6q_sabresd.c

add code as follow:

static inline void mx6q_sabresd_init_uart(void)

{

  imx6q_add_imx_uart(2, NULL);

  imx6q_add_imx_uart(0, NULL);

  // yuanmm add uart begin

  imx6q_add_imx_uart(1, NULL);

  imx6q_add_imx_uart(3, NULL);

  imx6q_add_imx_uart(4, NULL);

  // yuanmm add uart end

}

4,arch\arm\mach-mx6\Board-mx6q_sabresd.c

as ppt description, I should add code

early_console_setup(UART4_BASE_ADDR, uart_clk);

but I think this functiong is for console setting, so I didn't add this code for uart4

5, arch\arm\plat-mxc\include\mach\Uncompress.h

this fill already have follow code, so I didn't modify this code

  case MACH_TYPE_MX6Q_SABRESD:

  uart_base = MX6Q_UART1_BASE_ADDR;

  break;

[Rita_Wang · Accepted solution]

Hi mingmingyuan,

Your step is OK. Sorry for late reply. I wonder if your uart4 can work now?

Have a nice day
Dan

-----------------------------------------------------------------------------------------------------------------------
Note: If this post answers your question, please click the Correct Answer button. Thank you!
-----------------------------------------------------------------------------------------------------------------------

[Rita_Wang]

OK. If any questions you can contact me easily.