Re: KMS question

[Boszormenyi Zoltan]

2017-04-13 17:36 keltezÃssel, Alex Deucher Ãrta:
> On Thu, Apr 13, 2017 at 11:03 AM, Boszormenyi Zoltan <zboszor@xxxxx> wrote:
> > 2017-04-13 16:05 keltezÃssel, Alex Deucher Ãrta:
> > > On Thu, Apr 13, 2017 at 9:03 AM, Boszormenyi Zoltan <zboszor@xxxxx> wrote:
> > > > Hi,
> > > >
> > > > how can I disable the behaviour in the KMS drivers
> > > > that enables all outputs at once?
> > > >
> > > > It is very annoying that on a POS machine with an
> > > > 1024x768 LVDS and a 800x480 secondary monitor (both built-in)
> > > > the KMS driver wakes up both. Then the framebuffer console
> > > > and plymouth use both screens, making the primary output
> > > > very odd with only the top-left part used by the boot splash.
> > > >
> > > > I would like the boot splash to be shown only on the primary
> > > > output at its full resolution instead of on all outputs using
> > > > the smallest common rectangle.
> > > >
> > > > Is there a kernel command line configuration that achieves this?
> > > >
> > > > The device in question uses the gma500 kernel driver but the same
> > > > behaviour is observed with the i915 and radeon drivers.
> > >
> > > The problem is fbdev is not multi-head aware.  The fbdev emulation in
> > > the KMS drivers attempts to light up all monitors so that something
> > > shows up on all heads.  If you really want different per head
> > > configurations, you need to use the KMS API directly.  As a
> > > workaround, you can use the kernel command line to disable the output
> > > you don't want to be lit up.  See:
> > > https://wiki.archlinux.org/index.php/kernel_mode_setting
> > > for more info.  basically add video=TV-1:d to disable the output in
> > > question.  Replace TV-1 with whatever connector you want to disable.
> >
> >
> > I tried adding video=DVI-D-1:d to the kernel command line.
> >
> > The effect is while the second output is indeed disabled, the
> > framebuffer console still takes the second output's resolution
> > into account and the boot splash is still using only the top-left
> > 800x480 part of the 1024x768 primary screen.
> >
> > Also, the secondary screen got disabled also in X which is not desired.
> > Can I wake it up under X somehow? This device is using the modesetting
> > DDX driver.
>
> Can you enable it via randr?

No, "xrandr --output DVI-D-1 --auto" does nothing.

> Alex