I however found out that one can change the display resolution by making a change in U-boot.
For this purpose I replaced a part of bootargs with a variable, this reduces the endless typing and errorchances.
for this purpose I define a new variable bootargs_test, this is the same as bootargs_mmc except for the term dev=hdmi,1920x1080@60 video=mxcbf1: I replaced that with ${video}
Now the changes in videoresolution can be made in the variable video.
So fisrst setup the new bootargs:
- Code: Select All Code
setenv bootargs_test setenv 'bootargs ${bootargs} root=/dev/sda1 rootwait video=mxcfb1:dev=ldb,LDB-XGA,if=RGB666 video=mxcfb0:${video} off video=mxcfb2:off fbmem=28M consoleblank=0 quiet'
Please note that the rootfs is on sda1, if you don't have a rootfilesystem on SDA1 than root=/dev/mmcblk0p1, see bootargs_mmc
then we define the videovariable to get a lower resolution:
- Code: Select All Code
setenv video dev-hdmi,1080x720@M60 video=mxcbf1:
Now we setup a new bootcmd named bootcmd_test
- Code: Select All Code
setenv bootcmd_test run 'bootargs_base bootargs_test; mmc dev 3; mmc read ${loadaddr} 0x800 0x4000; bootm'
To make this defenite we change bootcmd otherwise you can type bootcmd_test to immediate boot
- Code: Select All Code
setenv bootcmd run bootcmd_test
- Code: Select All Code
saveenv
now boot and the display is 1080x720. So far so good.
What I would like to accomplish however is that I can change the resolution in ubuntu, if necesarry on commandline.
so I tried this:
I installed fbset (apt-get install fbset)
when booted in 1920x1010 I type fbset. I made notes of the information on the screen.
Now I edit /etc/fb.modes and add a mode 1920x1080-60 with the notes I made.
Save it and reboot, this time in 1280x720 as described above. Type fbset, make notes an add a mode 1280-x720-60 in /etc/fb.modes
Now I open a terminal in ubuntu and type fbset 1920x1080-60. The screen goes black
So why does this mode work if you boot in it and why not if you change to it with fbset?
Anyone any ideas?