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Linux/AM5718: Blue shadow appearing on LCD

Part Number: AM5718
Other Parts Discussed in Thread: TLC59108

Tool/software: Linux

Dear Team,

We developed the SBC with AM5718. We are using 10.4 SVGA LCD of NL8060BC26-35C from NEC and T-55787GD104J-LW-AHN from kyocera. In both the displays we are getting the blue shade for all fonts and images. Same panels are working with other SBC based on IMX6Q. What could be the reason. Please suggest how to proceed.

Kernel Version
4.1.13-g8dc6617


U-Boot Version
U-Boot 2015.07-00080-g4523775-dirty (Mar 08 2017 - 15:29:58 +0530)
arm-linux-gnueabihf-gcc (Linaro GCC 4.9-2015.05) 4.9.3 20150413 (prerelease)
GNU ld (GNU Binutils) Linaro 2014.11-3-git 2.24.0.20141017


Filesystem:
root@am57xx-evm:~# mount -v | grep "on /"
/dev/mmcblk0p2 on / type ext4 (rw,relatime,data=ordered)
devtmpfs on /dev type devtmpfs (rw,relatime,size=325092k,nr_inodes=81273,mode=755)
proc on /proc type proc (rw,relatime)
sysfs on /sys type sysfs (rw,relatime)
debugfs on /sys/kernel/debug type debugfs (rw,relatime)
tmpfs on /run type tmpfs (rw,nosuid,nodev,mode=755)
tmpfs on /var/volatile type tmpfs (rw,relatime,size=51200k)
/dev/mmcblk0p1 on /run/media/mmcblk0p1 type vfat (rw,relatime,gid=6,fmask=0007,dmask=0007,allow_utime=0020,codepage=437,iocharset=iso8859-1,shortname=mixed,errors=remount-ro)
devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620)


root@am57xx-evm:~# tune2fs -l /dev/mmcblk0p2
tune2fs 1.42.9 (28-Dec-2013)
Filesystem volume name:   rootfs
Last mounted on:          /
Filesystem UUID:          68e0dde0-ed15-4a0d-96d8-7174a6e920ef
Filesystem magic number:  0xEF53
Filesystem revision #:    1 (dynamic)
Filesystem features:      has_journal ext_attr resize_inode dir_index filetype needs_recovery sparse_super large_file
Filesystem flags:         unsigned_directory_hash
Default mount options:    user_xattr acl
Filesystem state:         clean
Errors behavior:          Continue
Filesystem OS type:       Linux
Inode count:              230608
Block count:              921856
Reserved block count:     46092
Free blocks:              3708
Free inodes:              163802
First block:              0
Block size:               4096
Fragment size:            4096
Reserved GDT blocks:      225
Blocks per group:         32768
Fragments per group:      32768
Inodes per group:         7952
Inode blocks per group:   497
Filesystem created:       Sat Jan  1 00:01:44 2000
Last mount time:          Thu Jan  1 00:00:03 1970
Last write time:          Thu Jan  1 00:00:03 1970
Mount count:              606
Maximum mount count:      -1
Last checked:             Sat Jan  1 00:01:44 2000
Check interval:           0 (<none>)
Lifetime writes:          4793 MB
Reserved blocks uid:      0 (user root)
Reserved blocks gid:      0 (group root)
First inode:              11
Inode size:               256
Required extra isize:     28
Desired extra isize:      28
Journal inode:            8
Default directory hash:   half_md4
Directory Hash Seed:      654d7d40-e70a-44c3-9c7a-26c1413cbcef
Journal backup:           inode blocks
root@am57xx-evm:~#



Thanks & Regards,
N.V.Subbaiah
  • Please post detailed information of your use case. Also post device tree settings related to the DSS and the log file. Also post the LCD hardware parameters and, if possible a picture of the screen effect you see.
  • Hi,

    we have interfaced 10.4" display. Here we are getting blue shadow and flickering on the left and right side edges of the panel.

    Please find the

    1. snaps and video for blue shade and white dots printing and going on left and right side of the panel

    2.dts file

    3.panel file

    4.boot log file

    https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/791/Flickering_5F00_BlueShade.7z

  • The issue that you are seeing is often caused by bad timings or polarities. Please check the timings and the polarities (vsync levels, data/de/sync edges) match what the panel wants. 

    Also, looks like you are using omapfb and have hacked panel-tlc59108.c driver for your need. panel-tlc59108.c driver is a combined driver for the TLC59108 LED chip and the panel used for DRA7 EVMs. It should not be used anywhere else, unless the HW design more or less matches that of DRA7 EVM, and has TLC59108

    If possible, you should switch to panel-dpi and supply the timings from the DT file, or if the panel require programming, write your own panel drivers. Also, switch  to omapdrm if the features don't depend upon omapfb. omapfb is no longer supported by TI.