Monitor doesn't display anything. EDID trouble ?

[Xavier Bestel]

Le lundi 24 octobre 2011 à 15:16 -0400, Alex Deucher a écrit :
> On Mon, Oct 24, 2011 at 3:01 PM, Xavier Bestel <xavier.bestel at free.fr> wrote:
> > Hi,
> >
> > I know it may be off-topic, but the experience is there.
> > I've just bought a used 30" monitor (HP ZR30w), and it doesn't display
> > anything, even at BIOS time. The backlight is on, but I see nothing
> > except a faint flickering at mode change times. Screen blanking works
> > (the backlight switches off). I'm using a Radeon HD 5700 via DVI,
> > debian/sid with kernel 3.1.0-rc7, Xorg 2:1.11.1.901-2 and radeon
> > 1:6.14.2-2.
> > After googling a bit, some people talk about a possible EDID problem
> > (apparently it's possible to have the EDID somehow erased from the
> > EEPROM ?). But Xorg.0.log does seem indicate that there's an EDID:
> >
> > [    21.829] (II) RADEON(0): Monitor name: HP ZR30w
> > [    21.829] (II) RADEON(0): Serial No: CN4048041Z
> > [    21.829] (II) RADEON(0): EDID (in hex):
> > [    21.829] (II) RADEON(0):    00ffffffffffff0022f06e2801010101
> > [    21.829] (II) RADEON(0):    3014010380402878ea8d85ad4f35b125
> > [    21.829] (II) RADEON(0):    0e505400000001010101010101010101
> > [    21.829] (II) RADEON(0):    010101010101e26800a0a0402e603020
> > [    21.829] (II) RADEON(0):    360081902100001abc1b00a050201730
> > [    21.829] (II) RADEON(0):    3020360081902100001a000000fc0048
> > [    21.829] (II) RADEON(0):    50205a523330770a20202020000000ff
> > [    21.829] (II) RADEON(0):    00434e343034383034315a0a20200066
> > [    21.829] (II) RADEON(0): Printing probed modes for output DVI-0
> > [    21.829] (II) RADEON(0): Modeline "2560x1600"x60.0  268.50  2560 2608 2640 2720  1600 1603 1609 1646 +hsync -vsync (98.7 kHz)
> > [    21.829] (II) RADEON(0): Modeline "1280x800"x59.9   71.00  1280 1328 1360 1440  800 803 809 823 +hsync -vsync (49.3 kHz)
> >
> > ... and then:
> >
> > [    21.854] (II) RADEON(0): Output DVI-0 using initial mode 2560x1600
> >
> > Does anyone have an idea how I could pinpoint the problem ?
> 
> The EDID looks ok to me.  Do any other modes work?  Try 1280x800.  Try
> the other DVI port.  If the neither port lights up the monitor
> (especially if the bios produces no display), it's probably a bad
> monitor.

OK, thanks to you I've found the problem
1) this monitor is apparently unable to display anything but 1280x800 or
2560x1600, so no BIOS nor GRUB for me.
2) my cable is single-link, so Xorg's default guess doesn't work.

After hooking a second monitor, and choosing 1280x800 for the big one,
everything's working (sort-of). I'll hunt for a dual-link or displayport
cable, whichever is cheapest.

Can Xorg detect if the cable is single-link ?

Thanks,
	Xav