Hi Merlin,
On 24.09.2016 21:25, Merlin Büge wrote:
Hello everyone!
This is my first post to this mailing list :)
welcome to coreboot ;)
I didn't have the time for a closer look at your logs. But there is one thing coreboot does definitely wrong: The clock configuration. You can see it from the Linux log as it dumps the settings coreboot made first:
[ 6.523864] [drm:drm_mode_debug_printmodeline] Modeline 0:"1440x900" 50 87075 1440 1520 1672 1820 900 903 909 961 0x40 0xa [ 6.523872] [drm:intel_dump_pipe_config] port clock: 87075
vs what Linux sets up later:
[ 8.787651] [drm:drm_mode_debug_printmodeline] Modeline 0:"1440x900" 60 104500 1440 1520 1672 1820 900 903 909 961 0x48 0xa [ 8.787668] [drm:intel_dump_pipe_config] port clock: 104500
Not sure why Linux doesn't get the display running though. But as Linux sometimes reuses register settings set by the firmware there is a slight chance that fixing coreboot would make it work in Linux too.
There is a related patch up for review for i945 [1] (older chipset) that fixes a similar issue there. Maybe it applies to gm45 too. The code looks very similar.
Regards, Nico
[1] https://review.coreboot.org/#/c/16504/
I'm trying to get a specific panel working on my Thinkpad T400 which runs libreboot. It's an WXGA+ MVA panel (CMO G141C1-L01) and I have soldered an adapter cable for it. From what I have found, nobody succeeded on this mod yet - there are some attempts on 51nb.com, but only for the T410. I basically took some already existing adapter cable, and modified a few pins, so that it would match up exactly with the datasheets. I used the LG LP141WP2-TLB1 for reference. Some details about my adapter cable can be found here:
http://forum.thinkpads.com/viewtopic.php?f=45&t=121151
In the first post there are also links to the datasheets of the two panels in question.
Of course I thoroughly checked all my self-made connections and modifications, but only with some general purpose DMM for continuity. They all seem fine.
So far backlight + PWM control works, but I have no image displayed, both in libreboot (with GRUB2 as payload) and Linux (up-to-date Arch Linux).
I tried the panel both with the latest stock ROM (3.23/EC 1.06) and with the latest libreboot release, which is currently 2016090 (t400_8mb_usqwerty_vesafb.rom in my case).
Since I have not much experience with such low-level hardware stuff, could someone maybe help me with this or direct me to some useful direction, how I can debug this?
I already tried booting with i915.lvds_channel_mode=2 (since I was not able to figure out what mode was actually used, because this module parameter is normally set to "0", which means the channel mode is taken from BIOS).
I attached the EDIDs of both panels, the coreboot log (cbmem -c) of both panels, and a kernel log of both panels. I also attached a kernel log of the MVA panel with drm debbuging enabled (drm.debug=0x1e log_buf_len=1M). Note that all of the logs were taken from the T400 with the latest libreboot release. It would be great if somebody could have a look at it. (I don't understand much of it.)
Here is a picture of the adapter cable, so that you have an idea what it looks like: https://lut.im/funPftuHF0/3sndAspbdiwOpTN4.jpg
I already put *a lot* of effort in this project, and I would be very happy if it succeeded at the end of the day. I would design some PCBs then, so that this would basically become a drop-in replacement. Background is: The T400 is a very desirable target for libreboot, since it's build on the latest Intel hardware currently supported in libreboot for laptops. And (not only in the libreboot community) it is sadly well known for its rather bad TN panels. Also, it would be something that I could give back to the libreboot community.
Since I have not much experience with mailing lists, please correct my of any 'bad' behavior.
Thank you for reading this, and for any advice in advance :)
Regards,
Merlin