topic Re: LVDS Display in i.MX Processors

LVDS Display

johnturnur — Thu, 07 Feb 2013 15:29:35 GMT

Hi,

I Want to get 1080P output on imx6, for Android OS.

I have follwoing qestions in my mind.

- What changes is required to get output on LVDS1 insted of LVDS0?

- It is possible to get 1080P output on LVDS with single changel? or do i need to use dual channel in spit mode? What are the changes required for that?

- Does current kernel support all this?

- Can you provide more detailed document for LVDS? ( I have IMX6DQRM.pdf)

John

Re: LVDS Display

SergioSolis — Wed, 13 Feb 2013 16:01:00 GMT

Hello John,

Which i.MX6 board are you using?, can I have the part number?...

Regarding some of your questions, yes, you can get 1080p output, yes, the kernel supports it.

Re: LVDS Display

johnturnur — Thu, 14 Feb 2013 07:48:23 GMT

I am using i.MX6q SABRE SDB smart device board.

Still i am not getting the LVDS output for 1080p, I got the output for 1366x768, but i want to get output for 2 channel LVDS.

Can you provide the detailed document?

Sugetsted Code chagnes.

Re: LVDS Display

VladanJovanovic — Thu, 14 Feb 2013 09:04:43 GMT

Please check SABRE_SD_Release_Notes_L3.0.35_1.1.0.pdf in Linux documentation package for available parameters to set up LVDS and framebuffer ("ldb=..." and "video=...").

Grepping through kernel sources for LDB-XGA should quickly get you to files where you should add your own LCD identifier (LDB-FULLHD or so) with timings that apply to your display.

Re: LVDS Display

saurabh206 — Thu, 14 Feb 2013 13:23:33 GMT

Hi,

To Get 1080p you need to use LDB split mode.

video=mxcfb0:dev=ldb,LDB-1080P60,if=RGB666 ldb=spl0 fbmem=24M

This should solved your problem.

Thanks,

Saurabh

Picustech Software

Re: LVDS Display

johnturnur — Fri, 15 Feb 2013 11:14:44 GMT

Its working for me.

But I am not able to output with 2 channel, 8-bit LVDS panel?

Is there any settting or modification is required for this?

Re: LVDS Display

soujanyak — Wed, 13 Mar 2013 13:11:06 GMT

Hello,

I am also trying to interface 1920X1200 LVDS display onto imx6 sabre-sd board, and i am trying to interface it on LVDS0,

i am unable to find the following answers :

(a)will IMX6 platform support 1920X1200 LVDS display ?

(b) what are the u-boot arguments i have to change

(d) and my 1920X1200 display is having a aspect ration of 16:10, is it supported by imx6 platform.

Can anyone kindly provide answers to my above questions.

Thanks

Re: LVDS Display

saurabh206 — Wed, 13 Mar 2013 13:50:49 GMT

Hi,

I am not sure about 1920x1200 but it should work,

- To add a support you need to modify the ldb.c file. update the ldb_modedb structure according to your panel's data sheet.

- video=mxcfb0:dev=ldb,LDB-1920P,if=RGB666 ldb=spl0

- single mode willnot work you need to use split mode.

Thanks,

Saurabh

Re: LVDS Display

SergioSolis — Wed, 13 Mar 2013 22:11:43 GMT

Yes, it does work on 1920x1200

Re: LVDS Display

soujanyak — Thu, 14 Mar 2013 10:04:22 GMT

Hello,

Thanks for your answers, but still i am unable to see anything on the display.

I am using the following u-boot arguments :

video=mxcdi0fb:RGB8880:dev=ldb,LDB-1920P,if=RGB888 ldb=spl0 fb0base=0x27b00000 fbmem=28M

My LVDS display is interfaced over 4LVDS data lanes ==>

LVDS0_TX0_N

LVDS0_TX0_P

LVDS0_TX1_N

LVDS0_TX1_P

LVDS0_TX2_N

LVDS0_TX2_P

LVDS0_TX3_N

LVDS0_TX3_P

so i am using if=RGB888 , is my analysis correct?

Apart from above the display i am using needs an aspect ration of 16:10, what code changes have to be done for this?

Thanks

Re: LVDS Display

saurabh206 — Thu, 14 Mar 2013 10:38:17 GMT

Hi,

Make sure that the values are the

static struct fb_videomode ldb_modedb[] are correct.

if color values are not set properly then you may get saturated output.

Thanks,

Saurabh

Picustech Software

Re: LVDS Display

Rooney — Mon, 18 Mar 2013 12:04:53 GMT

Hello!

I've troubles with the LVDS interface on the i.MX6Q as well.

I'm using the Variscite VAR-SOM-MX6 and connected a G121XN01 XGA LVDS display to the LVDS1 port.

The linux kernel is 3.0.35.

In U-Boot I use video=mxcfb0:dev=ldb,LDB-XGA,if=RGB24 ldb=sep1 as kernel command line.

I can see something on the display (see picture below) but unfortunately it is not the expected result. The resolution seems to be strange. The display even shows the same content three times, whereby at least on content (in the middle of the display) uses wrong colors.

If I use LDB-1080P60 instead of LDB-XGA (just for testing purpose) I would expect a difference, but there is none.

Does anyone have an idea what could be wrong? Do I need to do further configuration in the plattform specific code?

Regards,

Rooney

Re: LVDS Display

saurabh206 — Mon, 18 Mar 2013 12:52:59 GMT

Hi,

Can you try

" video=mxcfb0:dev=ldb,LDB-XGA,if=RGB666"

Thanks,

Saurabh Patel

Re: LVDS Display

Rooney — Mon, 18 Mar 2013 13:22:26 GMT

Hello Saurabh,

the only difference is the brightness of the shown tux, so the pixel format is okay.

In the meantime I could solve the problem. If I disable the configuration option FB_MXC_VAR_WVGA_SYNC_PANEL everything is working okay. This option is Variscite related and defines a specific LCD panel. Nevertheless it is strange that this results in such a strange behaviour. However, it works, thanks!!

Regards,

Rooney

Re: LVDS Display

soujanyak — Tue, 02 Apr 2013 11:43:47 GMT

Hello Saurabh,

I am trying to interface 1024RGB×768 LVDS display over LVDS0 interface on i.MX6, i am able to see the u-boot logo on the display but it is as shown below :

--> Linux kernel is 3.0.35 and the boot arguments are as below :

setenv bootargs console=ttymxc0,115200 init=/init rw video=mxcfb0:dev=ldb,LDB-XGA

-->The platform data is as below :

static struct fsl_mxc_ldb_platform_data ldb_data = {

.ipu_id = 1,

.disp_id = 0,

.ext_ref = 1,

.mode = LDB_SEP0,

.sec_ipu_id = 1,

.sec_disp_id = 1,

};

Kindly let me if there Is any other configuration that needs to be done in addition to above?

Thanks

Soujanya

Re: LVDS Display

fabio_estevam — Tue, 02 Apr 2013 13:31:16 GMT

Is this a custom board and LVDS panel? Looks like you need to adjust its timings in U-boot.

Check the displays struct in:

board/freescale/mx6qsabrelite/mx6qsabrelite.c

Re: LVDS Display

soujanyak — Fri, 05 Apr 2013 06:27:51 GMT

Thanks Estevam...

In u-boot i have adjusted the display timings and now i am able to boot my 1024X768 LVDS display (RGB666).

Hello,

Now i am trying to interface 1920X1200 LVDS display with i.MX6 processor, and this display is having RGB24 bits.

Following were the changes i made :

(a)In uboot-imx/board/freescale/mx6qsabrelite/mx6qsabrelite.c :

{

.bus = -1,

.addr = 0,

.pixfmt = IPU_PIX_FMT_LVDS888,

.detect = 0,

.enable = enable_lvds,

.mode = {

.name = "HYDIS-1920X1200display",

.refresh = 60,

.xres = 1920,

.yres = 1200,

.pixclock = 7692,

.left_margin = 100,

.right_margin = 40,

.upper_margin = 30,

.lower_margin = 3,

.hsync_len = 10,

.vsync_len = 12,

.sync = FB_SYNC_EXT,

.vmode = FB_VMODE_NONINTERLACED

}

(b)In u-boot kernel arguments i am configuring it as :

setenv bootargs $bootargs video=mxcfb0:dev=ldb,LDB-HYDIS,if=RGB888 fb=28M

(c)In the file : arch/arm/mach-mx6/board-mx6q_sabrelite.c

static struct ipuv3_fb_platform_data sabrelite_fb_data[] = {

{ /*fb0*/

.disp_dev = "ldb",

.interface_pix_fmt = IPU_PIX_FMT_RGB24,

.mode_str = "LDB-HYDIS",

.default_bpp = 24,

.int_clk = false,

}

static struct fsl_mxc_ldb_platform_data ldb_data = {

.ipu_id = 1,

.disp_id = 0,

.ext_ref = 1,

.mode = LDB_SPL_DI0,

.sec_ipu_id = 1,

.sec_disp_id = 1,

};

(d)In the file : drivers/video/mxc/ldb.c

according to 1920X1200 LVDS display timings :

static struct fb_videomode ldb_modedb[] = {

{

"LDB-HYDIS", 60, 1920, 1200, 6615,

30, 30,

15, 5,

60, 15,

FB_VMODE_NONINTERLACED,

FB_MODE_IS_DETAILED,},

}

With all the above changes also i am unable to see anything on the display?

What other configurations i need to take care inorder to enable 1920X1200 LVDS display.

Thanks

Soujanya

Re: LVDS Display

wodpine — Wed, 09 Jul 2014 01:08:02 GMT

Hi SerchMx,

I am using the i.MX6Q-SDB board, the default display port is LVDS1, I want to get output on LVDS0 port, what shall I do in the uboot ?

LVDS1 bootargs:

> setenv bootcmd booti mmc3

> setenv bootargs console=ttymxc0,115200 androidboot.console=ttymxc0 vmalloc=400M init=/init video=mxcfb0:dev=ldb,LDB-XGA,if=RGB666,bpp=16 video=mxcfb1:off video=mxcfb2:off fbmem=10M fb0base=0x27b00000

> saveenv

Re: LVDS Display

wodpine — Wed, 09 Jul 2014 01:13:52 GMT

Hi john

I use the same board like you now ! what shall i do so that i can change LVDS0 as outport port ?

Best Regard!

Re: LVDS Display

saurabh206 — Wed, 09 Jul 2014 03:39:49 GMT

Hi,

Add ldb=sin0 in bootargs.