i.MX ProcessorsのトピックRe: imx7d lcd display not working

imx7d lcd display not working

flabyjacob — Fri, 08 Nov 2019 16:28:20 GMT

hello all,

i am working on custom board based on imx7d SOC, in my custom board display is not working,

following are the things i have tried,

i have changed following entry in device tree:

&lcdif {
        pinctrl-names = "default";
        pinctrl-0 = <&pinctrl_lcdif_dat
                           &pinctrl_lcdif_ctrl>;

         display = <&display0>;
         disp-dev = "lcd";
      status = "okay";
display0: lcd-display {
           bits-per-pixel = <32>;
            bus-width = <24>;

         display-timings {
               native-mode = <&timing_vga>;
                  timing_vga: 800x480 {
                  clock-frequency = <25175000>;
                   hactive = <800>;
                  vactive = <480>;
                   hback-porch = <40>;
                  hfront-porch = <24>;
                  vback-porch = <32>;
                   vfront-porch = <11>;
                   hsync-len = <96>;
                   vsync-len = <2>;

                  de-active = <1>;
                   hsync-active = <0>;
                  vsync-active = <0>;
                  pixelclk-active = <0>;
          };

};
};
};

these changes are according to the lcd specification.

but still i cant get anything i the screen so how can i resolve this problem ?

please guide me .

any help will be greatly appreciated.

Re: imx7d lcd display not working

igorpadykov — Fri, 08 Nov 2019 23:41:40 GMT

Hi Flaby

example for 800x480 can be found in boundary devices imx7d-nitrogen7 board

linux-imx6/imx7d-nitrogen7.dts at boundary-imx_4.9.x_8mq_ga-pass1-ath10k · boundarydevices/linux-imx6 · GitHub

Best regards
igor
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Re: imx7d lcd display not working

flabyjacob — Sat, 09 Nov 2019 11:40:02 GMT

Hi igorpadykov,

thank you for your fast reply,

i tried with above example but still i cant get anything in the screen.

i am using parallel RGB display with 24 data lines,

please provide me some guidelines or help on this..?

also can you please tell me which driver is used and the driver path also..?

thanks and regards,

flaby

Re: imx7d lcd display not working

igorpadykov — Mon, 11 Nov 2019 05:26:58 GMT

one can recheck pinctrl_lcdif settings and check lcd signals with

oscilloscope.

Best regards
igor

Re: imx7d lcd display not working

flabyjacob — Mon, 11 Nov 2019 11:14:29 GMT

Hi igorpadykov,

thank you for your reply,

i got freescale logo from u-boot but when linux starts nothing is coming in display, i went through the devicetree of your reference

example for 800x480 can be found in boundary devices imx7d-nitrogen7 board
linux-imx6/imx7d-nitrogen7.dts at boundary-imx_4.9.x_8mq_ga-pass1-ath10k · boundarydevices/linux-imx6 · GitHub

and there is some issue and from my bootup log i can see that there is driver problem here are some lines,

mxc_lcdif lcd@0: err default_ifmt!
mxc_lcdif lcd@0: get lcd of property fail
mxc_lcdif: probe of lcd@0 failed with error -2
30730000.lcdif supply lcd not found, using dummy regulator
mxsfb 30730000.lcdif: failed to find mxc display driver lcd

actual bootup log is here ,

linux-bootup-log

please go through this log and give your advice,

your help is immensely appreciated.

thanks and regards,

flaby

Re: imx7d lcd display not working

igorpadykov — Mon, 11 Nov 2019 12:06:25 GMT

Hi Flaby

one can try to debug it, starting with probe function in

mxc_lcdif.c\mxc\fbdev\video\drivers - linux-imx - i.MX Linux kernel

Best regards
igor

Re: imx7d lcd display not working

flabyjacob — Mon, 11 Nov 2019 16:42:46 GMT

Hi igorpadykov,

thank you for your reply,

as per your suggestion

one can try to debug it, starting with probe function in
mxc_lcdif.c\mxc\fbdev\video\drivers - linux-imx - i.MX Linux kernel

we started debugging on the above driver code and as per the log we observed that probe function is running successfully but still we can't see anything on screen.

can you please tell me if i am missing anything.

Re: imx7d lcd display not working

igorpadykov — Tue, 12 Nov 2019 00:46:40 GMT

Hi Flaby

one can test lcd signals with oscilloscope (in particular clock) and

check them with lcd datasheet requirements.

Best regards
igor

Re: imx7d lcd display not working

flabyjacob — Tue, 03 Dec 2019 15:55:51 GMT

Hi igorpadykov,

thank you for your reply,

we took some break from our display related work,

as our display was working in u-boot and not in linux we compared the device-tree and found out that there is only one difference in lcd reset pin configuration i.e.

in uboot pin was configured as :MX7D_PAD_LCD_RESET__GPIO3_IO4 0x79

but in linux it is configured as : MX7D_PAD_LCD_RESET__LCD_RESET 0x79

we also changed this LCD_RESET pin in linux also and the display is working now.

i didn't understood this can you please tell me why it is not working with lcd reset pin configured as lcd reset.