[Intel-gfx] i915 and 1440p display w/ corrupt EDID

[Mathias Burén]

On 26 September 2014 08:25, Jani Nikula <jani.nikula at linux.intel.com> wrote:
> On Wed, 24 Sep 2014, Mathias Burén <mathias.buren at gmail.com> wrote:
>> I've a 1440p display with a non-sufficient/corrupt EDID.
>
> Just to double check, you mean the display really is broken in this
> regard, *not* that the driver is unable to read the EDID?

I think the EDID is broken as I got this monitor working with a
specific EDID file:
http://learnitwithme.com/wordpress/wp-content/uploads/2012/05/edid-shimian.bin
taken from this blog post on the subject: http://electron14.com/?p=342

>
> Does your monitor have other connections than HDMI? Can you try to see
> if they produce a valid EDID? It may be possible to use that EDID for
> HDMI using the EDID firmware mechanism.

Sorry no, it only has a dual DVI input, nothing else. (no HDMI)

>
>> When I connect the display to the laptop via the docking station, the
>> laptop detects that there is a display connected, but there are no
>> modes available. I can add a mode like this:
>
> Have you tried without the dock to reduce the number of failure points?

The laptop only has VGA and DP out unfortunately.

>
>> xrandr --newmode "2560x1440_60.0" 311.83 2560 2744 3024 3488 1440 1441
>> 1444 1490 -HSync +Vsync
>> xrandr --addmode HDMI3 2560x1440_60.0
>>
>> But I get an error when trying to use it: "xrandr: Configure crtc 1 failed".
>>
>> Does anyone have any tips on how to get the monitor working?
>
> Finally, dmesg with drm.debug=14 from boot to the problem, including the
> above attempt with xrandr, might prove useful.
>
> BR,
> Jani.
>
>
> --
> Jani Nikula, Intel Open Source Technology Center

Some logs:

cmdline: BOOT_IMAGE=/vmlinuz-3.17.0-997-lowlatency
root=/dev/mapper/vg0-root ro quiet threadirqs fastboot logo.nologo
elevator=deadline drm.debug=14

$ xrandr
xrandr: Output HDMI3 is not disconnected but has no modes
Screen 0: minimum 320 x 200, current 1600 x 900, maximum 32767 x 32767
LVDS1 connected primary 1600x900+0+0 (normal left inverted right x
axis y axis) 310mm x 174mm
   1600x900       60.0*+
   1440x900       59.9
   1360x768       59.8     60.0
   1152x864       60.0
   1024x768       60.0
   800x600        60.3     56.2
   640x480        59.9
VGA1 disconnected (normal left inverted right x axis y axis)
HDMI1 disconnected (normal left inverted right x axis y axis)
DP1 disconnected (normal left inverted right x axis y axis)
HDMI2 disconnected (normal left inverted right x axis y axis)
HDMI3 connected (normal left inverted right x axis y axis)
DP2 disconnected (normal left inverted right x axis y axis)
DP3 disconnected (normal left inverted right x axis y axis)
VIRTUAL1 disconnected (normal left inverted right x axis y axis)

dmesg | cat drm: http://pastebin.com/n8GjZNjA

Is there a way I can specify the Intel driver to use another EDID? By
the way, if I connect this display under Windows 7 I would normally
get a BSOD or it's not detected at all.

Regards
Mathias