How to change aspect ratio of LVDS display for iMX6Q-SABRE-SDB

[yuuki]

Dear all,

We test Dual Display of HDMI+LVDS on MX6Q-SABRE-SDB.
We use AndroidKK4.4.3_ BSP.

HDIM: FullHD(1920x1080)
LVDS: 1024x768 (attachment with SABRE-SDP)

We set a parameter of U-Boot as follows.

setenv bootargs console=ttymxc0,115200 androidboot.console=ttymxc0 consoleblank=0 vmalloc=400M init=/init video=mxcfb0:dev=hdmi,1920x1080M@60,if=RGB24 video=mxcfb1:dev=ldb,if=RGB666 video=mxcfb2:off video=mxcfb3:off androidboot.hardware=freescale cma=384M

The HDMI is output correctly.
However, the LVDS output does not match with LCD panel size.

The touch panel does not match the output size, too.

Please refer to an attached file.

The size seems to be output at 16:9

Would you tell me how to match the spectrum ratio with an LCD panel?

Best Regards,
Yuuki

[jimmychan · Accepted solution]

According to the User guide,  there is a kernel command (bootargs) in a table under section 5.4.2. Tells kernel/driver which resolution/depth and refresh rate should be used, or tells kernel/driver not to register a framebuffer device for a display device.

for example :

video=mxcfb0:dev=ldb,LDB-XGA,if=RGB666,bpp=32

It is matching the mode name "LDB-XGA" in the driver ldb.c. You may try to change the existing one or create a new one for your LVDS.

[christophertele]

hy,

sorry i dont get it. What did you expect?

1920x1080 is 16:9 and the display of the board 1024x768 is 4:3.

what you see on your picture is the proper way to show 16:9 content on a 4:3 panel.

otherwise it has to be streched.

[yuuki]

Dear Christopher Telemann-san,

Thank you for your response.

Now, 16:9 is displayed on the 4:3 panel.
We want to resize it from 16:9 to 4:3.

Can boot parameter set this?
We referred to Table11. "Common kernel boot parameters" in Linux_Release_notes, but were not able to find it.

If the change of the source code is necessary, would you tell me the modification?

Best Regards,
Yuuki

[christophertele]

im not shure if its possible to set different resolutions but try to pass the a resolution to the bootargs of mxcfb1.

maybe:

setenv bootargs console=ttymxc0,115200 androidboot.console=ttymxc0 consoleblank=0 vmalloc=400M init=/init video=mxcfb0:dev=hdmi,1920x1080M@60,if=RGB24 video=mxcfb1:dev=ldb,1024x768M@30,if=RGB666 video=mxcfb2:off video=mxcfb3:off androidboot.hardware=freescale cma=384M

you can also try to change the resolution after boot using fbset trough terminal.

[yuuki]

Dear Christopher Telemann-san,

Thank you for your support.

I tried it.

However, the problem was not settled.

We understood that it could not be set by U-Boot parameter.

Let us know if you know of any better way.

Best Regards,

Yuuki