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Multi-display - one monitor active but blank

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  Multi-display - one monitor active but blank Oliver Elphick <olly@lfix.co.uk> - 2016-03-21 22:10 +0100
    Re: Multi-display - one monitor active but blank Felix Miata <mrmazda@earthlink.net> - 2016-03-21 22:30 +0100
      Re: Multi-display - one monitor active but blank Mark Fletcher <mark27q1@gmail.com> - 2016-03-22 00:10 +0100
        Re: Multi-display - one monitor active but blank Oliver Elphick <olly@lfix.co.uk> - 2016-03-22 00:20 +0100
          Re: Multi-display - one monitor active but blank Lisi Reisz <lisi.reisz@gmail.com> - 2016-03-22 11:20 +0100
            Re: Multi-display - one monitor active but blank Ric Moore <wayward4now@gmail.com> - 2016-03-22 21:40 +0100
              Re: Multi-display - one monitor active but blank Oliver Elphick <olly@lfix.co.uk> - 2016-03-22 23:10 +0100
      Re: Multi-display - one monitor active but blank Felix Miata <mrmazda@earthlink.net> - 2016-03-22 02:00 +0100
        Re: Multi-display - one monitor active but blank Oliver Elphick <olly@lfix.co.uk> - 2016-03-22 10:50 +0100

#165792 — Multi-display - one monitor active but blank

I have two monitors; the second one sometimes comes to life but is
usually blank. However, the system thinks that it is active and
displaying.

The primary monitor is a Samsung 24" and the secondary (usually non-
functioning) one a Mirai  - Chi Mei Optoelectronics 22".  Just
occasionally the second monitor comes up and can be used normally, but
once the displays are turned off by the screen saver, it remains blank
when the display comes back.  However the "Displays" utility says that
it is in use.

Previously I avoided the problem by turning off the screen-savers and
leaving the monitors turned on 24 hours a day, but I have just
installed Debian (instead of Mint) and the problem has come back.

Any ideas where to start to solve this, please?


-- 
Oliver Elphick
Lincolnshire, England

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#165796

Oliver Elphick composed on 2016-03-21 21:01 (UTC):

> I have two monitors; the second one sometimes comes to life but is
> usually blank. However, the system thinks that it is active and
> displaying.

> The primary monitor is a Samsung 24" and the secondary (usually non-
> functioning) one a Mirai  - Chi Mei Optoelectronics 22".  Just
> occasionally the second monitor comes up and can be used normally, but
> once the displays are turned off by the screen saver, it remains blank
> when the display comes back.  However the "Displays" utility says that
> it is in use.

> Previously I avoided the problem by turning off the screen-savers and
> leaving the monitors turned on 24 hours a day, but I have just
> installed Debian (instead of Mint) and the problem has come back.

> Any ideas where to start to solve this, please?

Which Debian?

What gfxchip powers your displays? Maybe you hit a known bug, such as:
https://bugzilla.kernel.org/show_bug.cgi?id=94171

Show us Xorg.0.log and .xsession-errors and maybe we can help.
-- 
"The wise are known for their understanding, and pleasant
words are persuasive." Proverbs 16:21 (New Living Translation)

  Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!

Felix Miata  ***  http://fm.no-ip.com/

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#165800

[Multipart message — attachments visible in raw view] — view raw

It couldn't be a dodgy cable, could it?

Mark
On Tue, 22 Mar 2016 at 07:57, Oliver Elphick <olly@lfix.co.uk> wrote:

> On Mon, 2016-03-21 at 17:27 -0400, Felix Miata wrote:
> > Oliver Elphick composed on 2016-03-21 21:01 (UTC):
> >
> > >
> > > I have two monitors; the second one sometimes comes to life but is
> > > usually blank. However, the system thinks that it is active and
> > > displaying.
> > >
> > Which Debian?
>
> MATE testing
>
> # cat /etc/debian_version
> stretch/sid
>
> (up to date)
>
> > What gfxchip powers your displays?
>
> Card: Nvidia
> 01:00.0 VGA compatible controller: NVIDIA Corporation GT218 [NVS 300]
> (rev a2)
>
> (I hope that is an answer!)
>
> > Maybe you hit a known bug, such as:
> > https://bugzilla.kernel.org/show_bug.cgi?id=94171
>
> It is not the same chipset as reported in that bug, and I don't know
> what I'm doing well enough to play with randr at the moment.
>
> > Show us Xorg.0.log and .xsession-errors and maybe we can help.
>
> .xsession-errors does not exist, so far as I can see. As far as the
> system is concerned, it doesn't think that there is any error.
>
> Xorg.0.log attached. Both monitors are recognised.
>
> Thanks for any suggestions.
>
>
> --
> Oliver Elphick
> Lincolnshire, England
>

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#165801

On Mon, 2016-03-21 at 23:07 +0000, Mark Fletcher wrote:
> It couldn't be a dodgy cable, could it?
> 
> Mark

I don't think so. If that were the case it would flash on and off as
the cable moved. It is resolutely blank, except just sometimes. The
cable is behind the desk, so it doesn't ge tmoved.

It may have something to do with the momitor itself, but I don't have
another one to substitute.

Oliver

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#165816

On Monday 21 March 2016 23:13:22 Oliver Elphick wrote:
> On Mon, 2016-03-21 at 23:07 +0000, Mark Fletcher wrote:
> > It couldn't be a dodgy cable, could it?
> >
> > Mark
>
> I don't think so. If that were the case it would flash on and off as
> the cable moved. It is resolutely blank, except just sometimes. The
> cable is behind the desk, so it doesn't ge tmoved.
>
> It may have something to do with the momitor itself, but I don't have
> another one to substitute.
>
> Oliver

It would be worth trying another cable all the same, wouldn't it?  Or swapping 
them over if you haven't got another.  (Provided, of course, they are the 
same.)

Lisi

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#165839

On 03/22/2016 06:14 AM, Lisi Reisz wrote:
> On Monday 21 March 2016 23:13:22 Oliver Elphick wrote:
>> On Mon, 2016-03-21 at 23:07 +0000, Mark Fletcher wrote:
>>> It couldn't be a dodgy cable, could it?
>>>
>>> Mark
>>
>> I don't think so. If that were the case it would flash on and off as
>> the cable moved. It is resolutely blank, except just sometimes. The
>> cable is behind the desk, so it doesn't ge tmoved.
>>
>> It may have something to do with the momitor itself, but I don't have
>> another one to substitute.
>>
>> Oliver
>
> It would be worth trying another cable all the same, wouldn't it?  Or swapping
> them over if you haven't got another.  (Provided, of course, they are the
> same.)

I didn't see a response to the question if this was a laptop?



-- 
My father, Victor Moore (Vic) used to say:
"There are two Great Sins in the world...
..the Sin of Ignorance, and the Sin of Stupidity.
Only the former may be overcome." R.I.P. Dad.
http://linuxcounter.net/user/44256.html

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#165845

On Tue, 2016-03-22 at 16:36 -0400, Ric Moore wrote:
> 
> I didn't see a response to the question if this was a laptop?
> 

It isn't.  It's a tower PC. The on-board Intel video is not used; there
is a dual-head Nvidia card with both monitors.

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#165807

Oliver Elphick composed on 2016-03-21 22:56 (UTC):

> On Mon, 2016-03-21 at 17:27 -0400, Felix Miata wrote:

>> Oliver Elphick composed on 2016-03-21 21:01 (UTC):

>> > I have two monitors; the second one sometimes comes to life but is
>> > usually blank. However, the system thinks that it is active and
>> > displaying.

>> Which Debian?

> MATE testing

> # cat /etc/debian_version
> stretch/sid

> (up to date)

>> What gfxchip powers your displays?

> Card: Nvidia
> 01:00.0 VGA compatible controller: NVIDIA Corporation GT218 [NVS 300]
> (rev a2)

> (I hope that is an answer!)

According to the log, you have both NVidia and Intel gfx hardware, which to 
me means you're probably using a laptop, making my help available to you very 
limited. AFAIK, those two together are a special hybrid that for optimal use 
requires a special driver, either Bumblebee, or Prime, depending on whether 
you want a FOSS solution (latter), or a proprietary one (former).

Is it actually a PC with a separate NVidia card in a PCIe slot? If yes, are 
the cables actually both DisplayPort cables? Sometimes the logs identify 
connections differently from the actual physics. I've often seen physical DVI 
connectors identified as HDMI with Intel gfx hardware.

>> Maybe you hit a known bug, such as:
>> https://bugzilla.kernel.org/show_bug.cgi?id=94171

> It is not the same chipset as reported in that bug, and I don't know
> what I'm doing well enough to play with randr at the moment.

>> Show us Xorg.0.log and .xsession-errors and maybe we can help.

> .xsession-errors does not exist, so far as I can see. As far as the
> system is concerned, it doesn't think that there is any error.

> Xorg.0.log attached. Both monitors are recognised.

> Thanks for any suggestions.

First, ensure the display itself is not a problem by trying two things if you 
haven't already:

1-boot the computer with the 1920x1200 display powered off

2-if the cables are twins, boot the computer with the cables switched, so 
that the smaller is primary rather than the larger

Docs for solving such problems as yours are usually very good on Arch, so you 
might wish to look at https://wiki.archlinux.org/index.php/PRIME if nothing 
yet tried helps. Another place to look for video-focused help is:
https://lists.x.org/mailman/listinfo/xorg
-- 
"The wise are known for their understanding, and pleasant
words are persuasive." Proverbs 16:21 (New Living Translation)

  Team OS/2 ** Reg. Linux User #211409 ** a11y rocks!

Felix Miata  ***  http://fm.no-ip.com/

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#165815

On Mon, 2016-03-21 at 20:55 -0400, Felix Miata wrote:
> Oliver Elphick composed on 2016-03-21 22:56 (UTC):
> > > What gfxchip powers your displays?
> > 
> > Card: Nvidia
> > 01:00.0 VGA compatible controller: NVIDIA Corporation GT218 [NVS
> > 300]
> > (rev a2)
> > 
> > (I hope that is an answer!)
> According to the log, you have both NVidia and Intel gfx hardware,
> which to 
> me means you're probably using a laptop, making my help available to
> you very 
> limited. AFAIK, those two together are a special hybrid that for
> optimal use 
> requires a special driver, either Bumblebee, or Prime, depending on
> whether 
> you want a FOSS solution (latter), or a proprietary one (former).
> 
> Is it actually a PC with a separate NVidia card in a PCIe slot? If
> yes, are 
> the cables actually both DisplayPort cables? Sometimes the logs
> identify 
> connections differently from the actual physics. I've often seen
> physical DVI 
> connectors identified as HDMI with Intel gfx hardware.
> 

The latter is the case. The dual-head Nvidia card has both monitors;
the Intel port on the motherboard is not in use.

...

> First, ensure the display itself is not a problem by trying two
> things if you 
> haven't already:
> 
> 1-boot the computer with the 1920x1200 display powered off

The second (problem) display came up for the boot messages, but X still
treated the powered-off display as the primary display, so I had to
turn it on to log in. However the secondary display is currently
active, which is an improvement!
> 
> 2-if the cables are twins, boot the computer with the cables
> switched, so 
> that the smaller is primary rather than the larger

Bizarre results - the swapped primary (now secondary) was clearly using
the wrong driver settings, giving a very unclear picture, but both
screens came up.

On restoring things and rebooting, both screens came up.  I'll wait to
see what happens when it blanks the screen after inactivity.

> Docs for solving such problems as yours are usually very good on
> Arch, so you 
> might wish to look at https://wiki.archlinux.org/index.php/PRIME if
> nothing 
> yet tried helps. Another place to look for video-focused help is:
> https://lists.x.org/mailman/listinfo/xorg

Thanks for the suggestions.

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