Custom LCD mode not found by Linux

erezsteinberg — Wed, 13 May 2015 10:12:38 GMT

Hi experts,

I have a custom LCD that I connect to an iMX6DL, running Linux 3.10.53.

I made the following adjustments:

(1) Device-tree -- Updated relevant interface parameters. Changed mode_str for mxc_sdc_fb node to hold the new LCD string.

(2) In mxc_lcdif.c -- added new entry to lcdif_modedb[]

It seems the driver attempts to find the LCD mode in the modedb[], but the function 'mxcfb_check_var()' always returns 0.

I enabled DEBUG for device-driver printouts -

mxc_lcdif lcd.26: mxc_lcdif_probe enter

mxc_lcdif lcd.26: mxc_lcdif_probe exit

mxc_sdc_fb fb.25: mxcfb_probe enter

(NULL device *): Mode Str = CUSTOM_LCD

modedb fb_find_mode: mode option = CUSTOM_LCD

modedb fb_find_mode: Trying specified video mode (ignoring refresh rate) 0x0

modedb fb_find_mode: Trying best-fit modes

modedb fb_find_mode: Trying 800x480

modedb fb_try_mode: Trying mode CLAA-WVGA 800x480-4@57

modedb fb_try_mode: calling fb_check_var()

modedb fb_try_mode: Mode CLAA-WVGA -- err = 0

modedb fb_find_mode: Trying 800x480

modedb fb_try_mode: Trying mode SEIKO-WVGA 800x480-4@60

modedb fb_try_mode: calling fb_check_var()

modedb fb_try_mode: Mode SEIKO-WVGA -- err = 0

modedb fb_find_mode: Trying 320x240

modedb fb_try_mode: Trying mode CUSTOM_LCD 320x240-4@60

modedb fb_try_mode: calling fb_check_var()

modedb fb_try_mode: Mode CUSTOM_LCD -- err = 0

modedb fb_find_mode: Trying default video mode

modedb fb_try_mode: Trying mode CLAA-WVGA 800x480-24@57

modedb fb_try_mode: calling fb_check_var()

modedb fb_try_mode: Mode CLAA-WVGA -- err = 0

Any suggestions?

By the way-- if the LCD is defined in the DTB, do I also need to have video=... in bootargs?

Sincerely,

Erez

Re: Custom LCD mode not found by Linux

igorpadykov — Wed, 13 May 2015 14:18:41 GMT

Hi Erez

yes video=... in bootargs is also needed, for

example one can look at attached Release Notes

Table 11. Common Kernel Boot Parameters

from L3.10.53_1.1.0_LINUX_DOCS

Best regards

igor

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Custom LCD mode not found by Linux

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