linux-kernel - Re: screen goes blank when loading gma500

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Date:	Fri, 20 Mar 2015 12:34:13 +0300
From:	Michael Tokarev <mjt@....msk.ru>
To:	One Thousand Gnomes <gnomes@...rguk.ukuu.org.uk>
CC:	Linux-kernel <linux-kernel@...r.kernel.org>,
	dri-devel@...ts.freedesktop.org
Subject: Re: screen goes blank when loading gma500_gfx (atom D2500)

19.03.2015 23:05, One Thousand Gnomes wrote:
>> Yes, with video=LVDS-1:d boot parameter, kernel boots fine and there is
>> graphics/video output on the screen, with the following message from kernel
>> when loading gma500_gfx:
>>
>> [    6.472859] [drm] forcing LVDS-1 connector OFF
>>
>> (and a few others).
>>
>> There's one funky thing still -- the screen size is not calculated correctly
>> for the text (vga, d-sub) console, last text line is placed at about 3/4 of
>> the screen size, with the rest - 1/4 - of the screen being blank.
> 
> I've seen that in one other case, where what was in fact happening was
> that forcing the connector "off" was actually effectively leaving it as
> the BIOS set it.

When I use LVDS-1:d in the kernel command line, that connector is not shown
by utilities such as xrandr, at all.  There is, however, another connector,
named LVDS-0, and are also DVI-0, DVI-1, and DisplayPort-0, DisplayPort-1,
while this mobo only have DVI & D-SUB (and LVDS soldered on board too) and
no DP.  At least as far as I can see.  So at least one LVDS connector is
shown anyway (LVDS-0, not LVDS-1), and that one is "not connected".

Besides, DisplayPort-1 is shown as "connected" by xrandr, with monitor set
to 1024x768 mode, -- I think this is why the text VGA size is calculated
wrong.. Lemme see...

..nope.  Adding video=DisplayPort-1:d to the kernel command line (in
addition to video=LVDS-1:d) makes no difference, DisplayPort-1 is still
shown by xrandr as connected @1024x768.

>     What happens if you then use xrandr to change the
> display sizes ?

X11 works fine as far as I can see.  Xrandr works and changes video modes.
Once I switch from X back to the text console the text size occupes 3/4 of
the screen only, as if the monitor was smaller.

I wonder if it will work with more than one monitor... ;)  I'll try hopefully
today.

Thanks,

/mjt
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