Drive 1080p panel on two LVDS channels

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Drive 1080p panel on two LVDS channels

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Contributor I

Hi,

 
I'm working with an imx6duallite and I want to drive a 1920x1080 display with 2 LVDS channels but i came across a problem. Pictures are shown correctly on display but they have wrong colors (for example a blue bar during psplash is shown pink). It seems I'm using some wrong paramters. I read few thread where they told to active split-mode; I did it as you can see below, but it doesn't work.
 
my .dts has the following ldb:
 
&ldb {
  ipu_id = <1>;
  disp_id = <0>;
  ext_ref = <1>;
  mode = "sep0";
  sec_ipu_id = <1>;
  sec_disp_id = <1>;
  status = "okay";
  split-mode;

  lvds-channel@0{
    fsl,data-mapping = "spwg";
    fsl,data-width = <24>;
    crtc = "ipu1-di0";
    status = "okay";
  };

  lvds-channel@1{
    fsl,data-mapping = "spwg";
    fsl,data-width = <24>;
    crtc = "ipu1-di0";
    status = "okay";
  };
};
 
I also change the "bootargs" in u-boot to set "video" as:
 
video=mxcfb0:dev=ldb,LDB-19201080,if=RGB24,ldb=spl0 video=mxcfb1:off  
 
and in the ldb.c file I add the following: 
 
{
/* 1920x1080 @ 60 Hz */
" LDB-1920108 ",
60, //refresh
1920,  //xres
1080, //yres
7073, //pixclock
55, //left_margin
55, //right_margin
4, //upper_margin
4, //lower_margin
112, //hsync_len
12, //vsync_len
FB_SYNC_CLK_LAT_FALL,  // sync
FB_VMODE_NONINTERLACED,// vmode
FB_MODE_IS_DETAILED,   // flag
}, 
 
my display has the following parameters:
 
Clock frequency = 141.4 MHz
Refresh = 60 Hz
One line scannig period (Th) = 2142 clocks
Horizontal display period (Thd) = 1920 clocks
Frame period (Tv) = 1100 lines
Vertical display period (Tvd) = 1080 lines
 
Could  anyone tell me where is the mistake?
 
Thanks
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2 Replies

31 Views
NXP TechSupport
NXP TechSupport

Hi Andrea

one can try "split-mode = <1>;" as ldb driver uses "of_property_read_bool" in linux/drivers/video/fbdev/mxc/ldb.c :
https://source.codeaurora.org/external/imx/linux-imx/tree/drivers/video/fbdev/mxc/ldb.c?h=imx_4.1.15...
example of  split-mode = <1>; can be found on:
https://github.com/boundarydevices/linux-imx6/blob/boundary-imx_4.1.15_1.0.0_ga/arch/arm/boot/dts/im...

Best regards
igor
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Contributor I

Hi Igor, I tried your solution bU I still have problems. It seems my

display in set on a different configuration then Full Color but, as I can

see in the u-Boot environment, lcd_panel is LDB-19201080,if=RGB24 ldb=spl0.

Thank you for helping

2018-05-21 1:06 GMT+02:00 igorpadykov <admin@community.nxp.com>:

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Re: Drive 1080p panel on two LVDS channels

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