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From: Lukas Wunner <lukas@wunner.de>
To: Enrico Mioso <mrkiko.rs@gmail.com>
Cc: David Airlie <airlied@linux.ie>,
	Daniel Vetter <daniel.vetter@intel.com>,
	dri-devel@lists.freedesktop.org
Subject: Re: vga_switcheroo: MIS-using the DIS command on a muxless system
Date: Fri, 19 Jan 2018 10:41:23 +0100	[thread overview]
Message-ID: <20180119094123.GC25824@wunner.de> (raw)
In-Reply-To: <alpine.LNX.2.21.99.1801190836030.5225@mStation.localdomain>

On Fri, Jan 19, 2018 at 08:38:20AM +0100, Enrico Mioso wrote:
> I forgot one last question. Is there any way I can force the system
> to switch to the ATI card without installing a graphical environment,
> just out of curiosity?

As you've observed correctly, your particular machine isn't capable of
muxing the display, it's a muxless model.  Nowadays a mux is only found
on MacBook Pros  (can switch at runtime) and a few gaming laptops (can
only switch in BIOS).

On supported (i.e., pre-retina) MacBook Pros, it is indeed possible to
switch to the discrete GPU without a graphical environment, in fact
no graphical environment is even allowed to run currently.

If by "force the system to switch" you're not referring to muxing the
display but rather exercising (and thus powering on) the discrete GPU,
I believe you do need a graphical environment to start a client with
DRI_PRIME.  Failing that, you can try to force the GPU out of runtime
suspend with "echo on > /sys/bus/pci/devices/0000:01:00.0/power/control".
(Use "echo auto" to re-enable automatic power management.)

Kind regards,

Lukas
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       reply	other threads:[~2018-01-19  9:48 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <alpine.LNX.2.21.99.1801182123190.8539@mStation.localdomain>
     [not found] ` <20180118215958.GA25994@wunner.de>
     [not found]   ` <alpine.LNX.2.21.99.1801190836030.5225@mStation.localdomain>
2018-01-19  9:41     ` Lukas Wunner [this message]
2018-01-19 10:01       ` vga_switcheroo: MIS-using the DIS command on a muxless system Enrico Mioso

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