Try using vgabios of your Radeon HD 8650G ( " 1002,990b " graphic device of A10-5750M APU ) during coreboot compilation. According to G505s wiki page, currently AtomBIOS blob is needed for onboard VGA, but maybe its also needed for your working backlight?
I retrieved my vgabios via Linux kernel 3.19 using this method - http://www.coreboot.org/VGA_support#Retrieval_via_Linux_kernel .Then I downloaded latest sources of SeaBIOS & Coreboot, and build Coreboot using compiled SeaBIOS payload as well as vgabios file. My configuration is a bit similar to this one - http://www.coreboot.org/Supported_Motherboards#lenovo.2Fg505s - although some options were added and some removed since a time of that build.
In my understanding, vgabios needs to be extracted from a running machine. So just in case if your G505s is in bricked state and you can't run it for extraction of vgabios, I am sending it to you in attachments of this letter!
However I need to mention one interesting thing: *after *my laptop started running coreboot, what I retrieve via Linux kernel is now slightly different -- if to compare with what I used to retrieve *before *, while my laptop was still running a proprietary BIOS. And I have flashed coreboot rom into BIOS chip with file verification , so that doesn't seem to be a "bad flashing" case. Looks like Coreboot does not load a vgabios ROM inside it AS-IS, and instead modifies it slightly while loading...
So here are two bios files for you (could use any of them, maybe "before" one like I did) vgabios_before.bin - SHA1 checksum: e4d320eb278b0118c46e2e470e7154b12c41966d vgabios__after.bin - SHA1 checksum: a9e2ed569bbaaea283b5380a5f6c44fc4efc3da4
And here is a report about 3 bytes difference between them - http://www.diffnow.com/?report=2kwq3
P.S. What if your backlight problem could be related to manufacturer/model of LCD panel? For the reference, my panel is Samsung LTN156AT30L01 ( SDC Model 4652 ) which is working perfectly
On 4 April 2015 at 13:08, Vladimir quickcracktime@gmail.com wrote:
Very sorry to hear that your LCD backlight problem is not resolved yet! Are you confident that LCD backlight is not faulty, and have you tried reinstalling coreboot?
If answer for both questions is "yes", then you could try these two
advices:
- Redownload a source code of coreboot from github, compile it and flash
again to your G505s. Since your last try - at the end of January - there were 5 commits to "coreboot/src/mainboard/lenovo/g505s" branch, and also some commits to the common branches, changes that affect all the mainboards supported by coreboot. Maybe your issue will be resolved if you would try coreboot again, with latest sources!
- If 1st advice doesn't work, you could open
"coreboot/src/mainboard/lenovo/g505s/buildOpts.c" file (which is the only file from G505s branch that has a reference to "LCD") Go to line 158, try to change the "#define
BLDCFG_CFG_LCD_BACK_LIGHT_CONTROL
200" parameter. Default value seems to be 200 for most platforms, but you could try
setting
it to 0. Then compile & flash again
=== Any advices from experienced coreboot members would be very welcome!
===
On 3 April 2015 at 17:46, 1 1 zilogpnz@gmail.com wrote:
No. I not solved this problem.
2015-04-03 17:08 GMT+04:00 Vladimir quickcracktime@gmail.com:
On Mon Jan 26 13:07:42 CET 2015 zilogpnz wrote:
I'm trying to run Coreboot on Lenovo G505s and have a problem:
- backlight of LCD is not turn on. But on the external LCD (by CRT
connector) is all good.
Could you help me with a solution to this problem?
Sorry for such a long reply, but what is a current status of this problem? Have you resolved the LCD backlight problem with your G505s - and, if yes, how?