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#1 2012-11-12 14:43:11

The Compiler
Member
From: Winterthur, Switzerland
Registered: 2011-05-01
Posts: 142
Website

i915 - picture bigger than screen

Heya,

I'm having a weird problem with an industry-computer which is self-made by my company and Arch.

The display attached to it is an 800x600 display, but whatever I do, I get an 1024x768 picture on the 800x600 monitor, so basically this happens (click for full resolution):
gfx_fail_thumb.png

lcpci says this:

00:02.0 VGA compatible controller: Intel Corporation Mobile 4 Series Chipset Integrated Graphics Controller (rev 07)

xrandr says:

LVDS1 connected 1024x768+0+0 (0x45) normal (normal left inverted right x axis y axis) 0mm x 0mm

It seems the monitor does not know EDID:

get-edid: get-edid version 2.0.0
[...]
The EDID data should not be trusted as the VBE call failed.

uname -a:

Linux ipc 3.6.6-1-ARCH #1 SMP PREEMPT Mon Nov 5 11:57:22 CET 2012 x86_64 GNU/Linux

When I set a 800x600 resolution via xrandr, I get the same effect, but with 800x600 stretched to 1024x768 >_<
I tried some kernel options (video= and vga=) but without any luck.

I then tried to add modelines by hand via xrandr. First I tried an online modline generator which gave me this modeline:

"800x600" 39.80 800  824  872  960
                600  600  601  624

This basically does the same than before, 800x600 stretched and still the wrong portion of the screen.

Then I tried generating a modeline with cvt:

"800x600_60.00" 38.25 800 832 912 1024
                      600 603 607 624
                      -hsync +vsync

Then I read in the datasheet of the monitor:

Parameter                         Symbol     Min.  Typ.  Max.  Unit

Clock Frequency                   1/T_Clock   33.6  39.8  48.3  MHz
Vertical Section    Period        T_V        608   628   650    T_H
                    Active        T_VD       600   600   600    T_H
                    Blanking      T_VB         8    28    50    T_H
Horizontal Section  Period        T_H        920  1056  1240    T_Clock
                    Active        T_HD       800   800   800    T_Clock
                    Blanking      T_HB       120   256   440    T_Clock

So with that informations, I tried to do a modeline myself:

800x600 39.8 800 800 1056 1056
             600 600 628 628

Same as before.

I begin to think this might be a kernel or hardware bug of some sort.. Windows works fine though.
Also it's maybe worth mentioning I can change the screen resolution in the BIOS, and that is set to 800x600.

Some debug output:

if there's anything else you need to know, please let me know.

Florian


>>> from __future__ import braces
  File "<stdin>", line 1
SyntaxError: not a chance

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#2 2012-11-12 21:36:50

moetunes
Member
From: A comfortable couch
Registered: 2010-10-09
Posts: 1,024

Re: i915 - picture bigger than screen

It seems since X doesn't know the width and height of the monitor it's taken a guess which isn't right.
You can try measuring the monitor and using xrandr's --size option (in millimeters).
HTH


You're just jealous because the voices only talk to me.

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#3 2012-11-13 07:24:45

The Compiler
Member
From: Winterthur, Switzerland
Registered: 2011-05-01
Posts: 142
Website

Re: i915 - picture bigger than screen

moetunes wrote:

It seems since X doesn't know the width and height of the monitor it's taken a guess which isn't right.
You can try measuring the monitor and using xrandr's --size option (in millimeters).
HTH

Seems that does not work. I've also played with --mode, --fb and --fbmm a bit more, but it didn't help.
Maybe it's worth mentioning the same also happens in the framebuffer console, so I'm not sure if it's even an X problem, I guess it's more like DRI/KMS


>>> from __future__ import braces
  File "<stdin>", line 1
SyntaxError: not a chance

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#4 2012-11-13 08:14:18

pulce
Member
From: Italy
Registered: 2011-02-14
Posts: 64

Re: i915 - picture bigger than screen

You could try live booting with another distribution and see if it gets your screen size right, if it does then there's probably a solution for your problem.

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#5 2012-11-13 09:26:33

The Compiler
Member
From: Winterthur, Switzerland
Registered: 2011-05-01
Posts: 142
Website

Re: i915 - picture bigger than screen

pulce wrote:

You could try live booting with another distribution and see if it gets your screen size right, if it does then there's probably a solution for your problem.

In other distris (older kernels) the graphics don't work at all. Actually, with 3.5 or so I had the same problem, but the screen was also split in half, and the left half was showing up on the right side, the right half on the left side. Looked pretty weird big_smile

Anyways, if there isn't anyone saying I've done something wrong in the next few days, I'm probably going to submit a kernel bug.


>>> from __future__ import braces
  File "<stdin>", line 1
SyntaxError: not a chance

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