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Date:      Wed, 4 Dec 2019 13:28:18 -0600
From:      CyberLeo Kitsana <cyberleo@cyberleo.net>
To:        Polytropon <freebsd@edvax.de>, FreeBSD Questions <freebsd-questions@freebsd.org>
Subject:   Re: How to force X to use a specific GPU / output
Message-ID:  <1778c19d-7ae2-a1cf-a3f6-f6f1a9e8b43c@cyberleo.net>
In-Reply-To: <20191130210239.ff69c8a2.freebsd@edvax.de>
References:  <20191130210239.ff69c8a2.freebsd@edvax.de>

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On 11/30/19 2:02 PM, Polytropon wrote:
> With a HP Pavilion dm-1 "netbook" laptop I got, I have a problem
> since I connected a HDMI display: There are now several green
> pixels on the screen, in areas where the color is nearly black.
> They also appear in videos and make the "compression squares"
> visible.
> 
> Note: Those are _not_ defective pixels on the display.
> 
> When the system boots up, everything is fine. As soon as the
> system enters X, color isn't displayed properly as before.
> The video output on both HDMI and VGA, even at the same time,
> shows the colors correctly.
> 
> During searches related to that problem, I once found an image
> that looked like what I'm seeing, and I read an article, even
> though regarding a Macbook, that this problem occurs due to
> internal switching between graphics hardware depending on if
> the internal screen should be driven or an external one. Sadly,
> I cannot find any of those again...
> 
> However, I found this:
> 
> http://cdn.avsforum.com/3/3e/3e8d725c_vbattach231475.png
> 
> You can see "green clouds" around the curves, and the colors
> look slightly distorted. Everything that is "nearly black" now
> looks green - the _same_ green. The image above shows that
> problem on something that looks like "Windows 7".

<snip>

This looks very much like what happened to several of my old Gateway 
desktop LCDs when their internal LVDS connector became loose and started 
slipping off the back of the display panel assembly. Who holds a 
high-speed data connector in place with masking tape, anyways?

> What worries me most:
> 
> The display was _fine_ before connecting a HDMI TV as external monitor!

This may be a coincidence.

If you can (and are willing to) disassemble the netbook, double-check 
that the LCD cable is securely connected at both ends, that the 
connectors are free of corrosion, and that the cable is not being frayed 
or damaged by hinge movement.

-- 
Fuzzy love,
-CyberLeo

<CyberLeo@CyberLeo.Net>
Technical Administrator

CyberLeo.Net Webhosting
http://www.CyberLeo.Net

Element9 Communications
http://www.Element9.net


Furry Peace! - http://www.fur.com/peace/



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