topic Interfacing i.mx8 mini (SOM) with LCD in i.MX Processors

Interfacing i.mx8 mini (SOM) with LCD

purendra_singh — Mon, 21 Sep 2020 06:22:16 GMT

Hello,

I am working on a project using Variscite's Dart mx8m mini board and have to interface a LCD which has

Make:- YOURI

Model:- ET020HV03-OT

LCD Driver IC :- ST7796S

I am going to use yocto version ZEUS (Kernel version 5.4.3) and MIPI DSI to interface LCD to imx board.

What are the steps that I should follow to get my LCD working? Because I am new to linux and have very minimal idea about it.

Do I have to write some custom driver code for LCD and if yes, can I get some reference for it?

Also if there is any document that can be helpful please suggest.

Thanks

Re: Interfacing i.mx8 mini (SOM) with LCD

igorpadykov — Mon, 21 Sep 2020 09:23:52 GMT

Hi purendra_singh

for new MIPI-DSI lcd one can start with imx8mm-evk-rm67191.dts

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm64/boot/dts/freescale/imx8mm-evk-rm67191.dts?h=imx_5.4.24_2.1.0

add specific for that lcd initialization in driver : struct cmd_set_entry manufacturer_cmd_set[],

timings in struct drm_display_mode default_mode

https://source.codeaurora.org/external/imx/linux-imx/tree/drivers/gpu/drm/panel/panel-raydium-rm67191.c?h=imx_5.4.24_2.1.0

Best regards
igor

Re: Interfacing i.mx8 mini (SOM) with LCD

purendra_singh — Thu, 24 Sep 2020 09:16:01 GMT

Thanks Igor

I have been provided initialization sequence for the LCD by vendor. When I went through the ST7796s driver's datasheet and matched the sequence I found out that

1.VFP (Vertical front porch):- 0x08

2.VBP (Vertical back porch):- 0x08

3.HBP (Horizontal Back porch):- 0x64

have been set in the sequence by using the command BPC(B5): Blanking Porch Control but didn't get Horizontal front porch value, hsync_len and vsync_len.

I am taking reference from below link to calculate the pixel clock :-

https://community.nxp.com/t5/i-MX-Processors-Knowledge-Base/Setting-i-MX8M-Mini-and-Nano-MIPI-DPHY-Clock/ta-p/1104457

Also I have got the table below, can I take Horizontal front porch value, hsync_len and vsync_len from this table. Which values should I take ? Please suggest.

Thanks.