i.mx6 parallel LCD framebuffer question

[eric_lee1]

I am working on i.MX6 custom board. The kernel version is 3.14.28. We use 24-bit parallel RGB LCD interface connecting to a 7-inch 800x480 panel. I can see the pengium picture and console text showing on LCD. The rootfs is ubuntu 14.04. When I try to verify the framebuffer device, I cat a raw image that is used in our standard testing to /dev/fb0. I got

root@arm:~# cat rgb800480.raw >/dev/fb0

cat: write error: No space left on device

root@arm:~#

Also

root@arm:~# cat /dev/zero >/dev/fb0

cat: write error: No space left on device

root@arm:~#

Did I miss anything?

The parameter pass to kernel is

optargs="video=mxcfb0:dev=lcd,CLAA-WVGA,if=RGB24,bpp=24 consoleblank=0 fbmem=24M vmalloc=400M"

Plus, when proforming "fbset" under ubuntu 14.04, I got

root@arm:~# fbset 800x600-60

mxc_sdc_fb fb.25: cannot get pixel format

mxc_sdc_fb fb.25: cannot get pixel format

imx-ipuv3 2400000.ipu: WARNING: adapt panel end blank lines

mxc_sdc_fb fb.25: cannot get pixel format

mxc_sdc_fb fb.25: cannot get pixel format

imx-ipuv3 2400000.ipu: mxc ipu: unimplemented pixel format

imx-ipuv3 2400000.ipu: Unsupported burst size 1

mxc_sdc_fb fb.25: cannot get pixel format

imx-ipuv3 2400000.ipu: mxc ipu: unimplemented pixel format

mxc_sdc_fb fb.25: cannot get pixel format

mxc_sdc_fb fb.25: cannot get pixel format

imx-ipuv3 2400000.ipu: mxc ipu: unimplemented pixel format

mxc_sdc_fb fb.25: cannot get pixel format

mxc_sdc_fb fb.25: timeout when waiting for flip irq

mxc_sdc_fb fb.25: cannot get pixel format

mxc_sdc_fb fb.25: timeout when waiting for flip irq

mxc_sdc_fb fb.25: cannot get pixel format

mxc_sdc_fb fb.25: timeout when waiting for flip irq

root@arm:~#

Could you help me out? Thanks.@

[saurabh206]

Hi Lee

Your setting is correct.

You should able to rgb800480.raw content on screen if display bpp and image bpp matches.

dd if=rgb800480.raw  of=/dev/fb0

You can used following commands to check supported display modes

cat /sys/class/graphics/fb0/modes

And you can set using

echo U:1280x720p-60 > /sys/class/graphics/fb0/mode

Thanks

Saurabh

[eric_lee1]

Hi Saurabh,

When passing bpp=32 parameter to kernel, I have no problems with that. However, it seems that I can only choose those bpp=32 ones in the /etc/modes to avoid this kind of errors when performing fbset. Does the i.mx6 lcd driver only limit user using 32 bit bpp? How to work around this?

I meant if you fbset to a mode that bpp is not equal to 32. You will get errors.