Re: [Libreboot-dev] Working T60 with 1024x768 panel

[Denis 'GNUtoo' Carikli]

On Tue, 17 May 2016 09:04:24 +0100
Leah Woods <address@hidden> wrote:
> Hi Denis,
Hi,

> > I've a T60 with a 1024x768 panel that appear to work with 
> > coreboot(-libre)
> > 
> > I've dumped the EDID: - By copying Linux-libre's
> > /sys/class/drm/card0-LVDS-1/edid - By dumping the flash chip with
> > i2cdump.
[...]
> Can you prepare a patch for libreboot?

Finding out which panel this computer has is not straightforward.

I followed the documentation[1], and all I could get was:
> $ parse-edid < edid.kernel
> Checksum Correct
> 
> Section "Monitor"
>       Identifier "�����"
>       ModelName "�����"
>       VendorName "LEN"
>       # Monitor Manufactured week 50 of 2005
>       # EDID version 1.3
>       # Digital Display
>       DisplaySize 300 230
>       Gamma 2.20
>       Option "DPMS" "true"
>       Modeline        "Mode 0" 65.00 1024 1048 1184 1344 768 771
> 777
806 -hsync -vsync Modeline      "Mode 1" 54.16 1024 1048 1184 1344
> 768 771 777 806 -hsync -vsync EndSection

The "LEN" (probably for lenovo) vendor is not very indicative.

Until some minutes ago, I had no idea what the LCD model was.

However if looked at it again and I spotted a strange string in the
decoded EDID in the cbmemc log: "N150X3-L0A".

Looking that up on a search engine finds that "N150X3-L0A" corresponds
to an LCD model from "Chi Mei Optoelectronics Corp" and the
corresponding datasheet[2] seem to confirm it.

I'll send the patch for adding that string to the documentation, however
the process of finding out the model here requires to have coreboot or
libreboot already flashed.

This isn't very convenient when buying such laptop.

Here the solution would be to either:
- Find better software to decode the EDID
- Write a more complete EDID decoder, for instance in a library, and
  use it in an application that would check if it's compatible with
  libreboot.

Then the documentation should be updated again to make use of that
when checking for the LCD compatibility.

References:
-----------
[1]https://libreboot.org/docs/misc/index.html#get_edid_panelname
[2]http://www.notebook-lcd.ru/pdf/N150X3_L0A.pdf

Denis.

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