From: Alex Deucher <alexdeucher@gmail.com>
To: Boszormenyi Zoltan <zboszor@pr.hu>
Cc: lkml <linux-kernel@vger.kernel.org>,
Maling list - DRI developers <dri-devel@lists.freedesktop.org>
Subject: Re: KMS question
Date: Thu, 13 Apr 2017 11:36:45 -0400 [thread overview]
Message-ID: <CADnq5_Pae2FnCcTSz72Z38Z1zJ1dPts4VsVVtWL5-K_-E29kLA@mail.gmail.com> (raw)
In-Reply-To: <cfdb221a-a7fb-503c-14fb-ca6caf2c4332@pr.hu>
On Thu, Apr 13, 2017 at 11:03 AM, Boszormenyi Zoltan <zboszor@pr.hu> wrote:
> 2017-04-13 16:05 keltezéssel, Alex Deucher írta:
>>
>> On Thu, Apr 13, 2017 at 9:03 AM, Boszormenyi Zoltan <zboszor@pr.hu> 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?
Alex
next prev parent reply other threads:[~2017-04-13 15:36 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-13 13:03 KMS question Boszormenyi Zoltan
2017-04-13 14:05 ` Alex Deucher
2017-04-13 15:03 ` Boszormenyi Zoltan
2017-04-13 15:36 ` Alex Deucher [this message]
2017-04-13 15:37 ` Ilia Mirkin
2017-04-13 16:20 ` Ville Syrjälä
2017-04-13 17:32 ` Boszormenyi Zoltan
2017-04-13 15:48 ` Boszormenyi Zoltan
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