I installed ubuntu Image in my iMX6 sabre lite board.
I want to use LVDS as default output, so I changed the u-boot environment as below:
setenv bootargs_mmc 'setenv bootargs ${bootargs} root=/dev/mmcblk1p1 rootwait rw video=mxcfb0:dev=ldb,1920x1080M@60,if=RGB666', then saveenv and reset.
I saw the log from concole is "ldb ldb.14: failed to find valid LVDS channel".
The HDMI output can work normally. In the uboot, it shows:
U-Boot 2016.03-20415-ged95621 (Jul 07 2016 - 17:28:42 -0700), Build: jenkins-ub4
CPU: Freescale i.MX6Q rev1.2 at 792 MHz
Reset cause: POR
Board: SABRE Lite
I2C: ready
DRAM: 1 GiB
MMC: FSL_SDHC: 0, FSL_SDHC: 1
SF: Detected SST25VF016B with page size 256 Bytes, erase size 4 KiB, total 2 MiB
auto-detected panel 1280x720M@60
Display: hdmi:1280x720M@60 (1280x720)
In: serial
Out: serial
Err: serial
Net: Micrel ksz9021 at 6
FEC [PRIME]
Error: FEC address not set.
, usb_ether
Hit any key to stop autoboot: 0
How can I change the default panel from HDMI to LVDS?
Hi,
Please read our blog posts entirely. The image you are using comes from here:
https://boundarydevices.com/mx-linux-kernel-3-14-52/
At the end of the post it is said:
"
U-Boot is in charge of setting the display parameters in the device tree. So it requires to use U-Boot v2015.07 or higher. Please make sure to read our blog post about this release:
https://boundarydevices.com/compiling-latest-u-boot-for-i-mx6-2015-edition
"
Everything is explained there. Hope this helps.
Regards,
Gary
Hi,
What you changed is bootargs for Linux kernel and therefore Linux will try to use LVDS port as display. However what you show us is the output of u-boot and it does not have much to do with Linux display configuration.
You mention "ldb ldb.14: failed to find valid LVDS channel".
Are you sure LVDS port is configured correctly? Show us your device tree.
Hi,
The uboot and Ubuntu image is downloaded from official website, I did not change anything yet, Do you mean I need to download the BSP sourcecode and modify the LVDS config file then rebuild BSP?
Hi,
If you want to change your U-boot default display, you should definitely modify U-boot source.
However, if you just want to change Ubuntu display, what you did seems correct to me. But because you are getting that ldb error, the only reason I can think of is that LVDS is not enabled in device tree.
What does the documentation say? LVDS enabled by default?
I just want to change Ubuntu display, I saw the log in serial console shows that "LVDS disabled", how to enable LVDS? which document can be referenced for the issue?
You said that U-boot and Ubuntu image are downloaded from official website. Surely, there must be some documentation there?
If LVDS is disabled, you should either find a precompiled .dts file with LVDS enabled for your board or you should do that yourself. Download kernel source, enable LVDS in device tree, compile and deploy.
BTW, I run printenv in u-boot, the log shows as below:
cmd_hdmi=fdt set fb_hdmi status okay;fdt set fb_hdmi mode_str 1280x720M@60;
cmd_lcd=fdt set fb_lcd status disabled
cmd_lvds=fdt set fb_lvds status disabled;fdt set ldb/lvds-channel@0 status disab
led
the lvds status is disabled, can I enable it in u-boot?
When power on the board, I noticed that the backlight of LVDS panel flick some times.
Below is the log:
U-Boot 2016.03-20415-ged95621 (Jul 07 2016 - 17:28:42 -0700), Build: jenkins-ub4
CPU: Freescale i.MX6Q rev1.2 at 792 MHz
Reset cause: POR
Board: SABRE Lite
I2C: ready
DRAM: 1 GiB
MMC: FSL_SDHC: 0, FSL_SDHC: 1
SF: Detected SST25VF016B with page size 256 Bytes, erase size 4 KiB, total 2 MiB
Display: hdmi:1280x720M@60 (1280x720)
In: serial
Out: serial
Err: serial
Net: Micrel ksz9021 at 6
FEC [PRIME]
Error: FEC address not set.
, usb_ether
Hit any key to stop autoboot: 0
AHCI 0001.0300 32 slots 1 ports 3 Gbps 0x1 impl SATA mode
flags: ncq stag pm led clo only pmp pio slum part
No port device detected!
** Bad device size - sata 0 **
SATA device 1: unknown device
** Bad device sata 1 **
MMC: no card present
MMC: no card present
** Bad device mmc 0 **
switch to partitions #0, OK
mmc1 is current device
4437 bytes read in 29 ms (149.4 KiB/s)
## Executing script at 10008000
** File not found uEnv.txt **
42869 bytes read in 1207 ms (34.2 KiB/s)
only CEA modes allowed on HDMI port
----------- trying to load /initrd.img
2317536 bytes read in 280 ms (7.9 MiB/s)
5499904 bytes read in 499 ms (10.5 MiB/s)
Kernel image @ 0x10800000 [ 0x000000 - 0x53ec00 ]
## Flattened Device Tree blob at 13000000
Booting using the fdt blob at 0x13000000
reserving fdt memory region: addr=13000000 size=b000
Using Device Tree in place at 13000000, end 1300dfff
Starting kernel ...
ldb ldb.14: failed to find valid LVDS channel
fec 2188000.ethernet (unregistered net_device): Invalid MAC address: 00:00:00:00
snvs_rtc 20cc034.snvs-rtc-lp: can't get snvs-rtc clock
imx6q-pcie 1ffc000.pcie: phy link never came up
imx6q-pcie 1ffc000.pcie: Failed to bring link up!
imx6q-pcie 1ffc000.pcie: failed to initialize host
ili210x_i2c 2-0041: i2c transfer failed
ili210x_i2c 2-0041: Failed to get firmware version, err: -5
tsc2004_reset: write_cmd -5
tsc2004 2-0048: Failed to reset TSC -5
adv7180 2-0020: adv7180_read:read reg error: reg=11 ret=-5
egalax_ts 2-0004: Failed to read firmware version
ft5x06-ts 2-0038: ft5x06: Could not detect touch screen -19.
tc358743_read_reg:reg=0 ret=-5
tc358743_probe:cannot find camera
tc358743_probe: failed, error=-19
ov5640_read_reg:write reg error:reg=300a
mxc_v4l_open: Mxc Camera no sensor ipu0/csi0
mxc_v4l_open: Mxc Camera no sensor ipu1/csi0
mxc_v4l_open: Mxc Camera no sensor ipu0/csi0
mxc_v4l_open: Mxc Camera no sensor ipu1/csi1
update_device_addr: ov5640_mipi ret=-5
ov5640_read_reg(mipi):reg=300a ret=-5
update_device_addr: ov5642 ret=-5
ov5642_read_reg:write reg error:reg=300a
[ OK ]
saned disabled; edit /etc/default/saned
Ubuntu 14.04.4 LTS nitrogen ttymxc1