IMX8M-MINI kernel programming for GPIO to interface parallel camera and lcd.

[vivek338]

Hi,

I want to interface parallel camera and parallel lcd with imx8 using gpio pins. But using libgpiod the frequency of gpio is very low(approx. 300KHz). Camera or lcd requires atleast 30MHz on gpio pins. As imx8mmini comes with dsi which is serial interface also imx8x have only 8-bit parallel interface. After some research I found that we can increase frequency of gpio using direct register programming in kernel space. So how to program gpio in kernel space and is there any other processor for parallel camera/lcd interface and how to do on that processor?

Please help!!!!!!!!

[Dhruvit]

Hi @vivek338 ,

I hope you are doing well.

when you connect to lcd or camera to imx8m mini , do you configure gpio pins as a i2c to connect a camera or LCD module with imx8m mini ? if not then for what purpose you want to use gpio ,can you enlighten me more ?

Thanks & Regards

Dhruvit Vasavada

[vivek338]

Thanks for rply!!

I did not configure i2c. GPIO is used for tranferring clock and data to lcd, its parallel rgb lcd with Hsync, Vsync, Psync and DE clocks required and 16/24 bit parallel data latch over Psync.

[Dhruvit]

Hi @vivek338,

->In iMX8m mini one can get an 8-bit parallel gpio pin for MIPI-DSI, and if one has to increase the frequency on gpio then one has to write a driver code for it because using libgpiod which is a userspace library that will cause kernel overhead & eventually frequency got down, that's why max. freq. 300 kHz can be achieved only.

->Also for RGB LCD 24-bit parallel gpio pins will be required & even the iMX8x series don't have it either, so one has to specifically write 24-bit driver code for the same, for which one can get higher frequency by configuring a fast slew rate for gpio pad.

Thanks & Regards.

Dhruvit Vasavada.