VGA_Switcheroo Is Getting Modernized With Device Link Support

[phoronix]

Phoronix: VGA_Switcheroo Is Getting Modernized With Device Link Support

VGA_Switcheroo is the Linux kernel component for dealing with MUX'ed and MUX-less hybrid graphics laptops/systems for switching between GPUs. A new patch series is working to modernize and improve VGA Switcheroo...

http://www.phoronix.com/scan.php?page=news_item&px=VGA-Switcheroo-Modernized

[tildearrow]

Typos:

Lukas is using device links with VGA_Switcheroo for enforcing a runtime power management dependent on an HDA controller to the GPU it's integtated into and by making use of this newer kernel API allows dropping some obsolete code that in the process also fixes "a bunch of bugs."

This might also yield a small power savings if a discerete GPU is being used but not its HDA controller, since now that audio controller can be run-time suspended to a D3hot stage.

[Michael]

Typos:

Thanks, this Raven Ridge (trying to) test is wrecking my mind this weekend.

[starshipeleven]

No wait. I thought VGA switcheroo is used only when there are actually muxed outputs (i.e. the physical video port is attached to a switch, that either routes it to the iGPU or the dGPU.

What is VGA switcheroo doing if there is no mux?

I generally approve MUXing as it's much easier to deal with than sharing load with a headless GPU as most modern systems.

[oiaohm]

No wait. I thought VGA switcheroo is used only when there are actually muxed outputs (i.e. the physical video port is attached to a switch, that either routes it to the iGPU or the dGPU.

What is VGA switcheroo doing if there is no mux?

I generally approve MUXing as it's much easier to deal with than sharing load with a headless GPU as most modern systems.

https://www.kernel.org/doc/html/v4.14/gpu/vga-switcheroo.html

Power management on muxless. Its in the manual.

[etam]

https://www.kernel.org/doc/html/v4.14/gpu/vga-switcheroo.html

Power management on muxless. Its in the manual.

How does that compare to bbswitch?

[oiaohm]

How does that compare to bbswitch?

https://github.com/Bumblebee-Project/Bumblebee/tree/master/src/switch

bbsswitch comes from Bumblebee do notice here they are using VGA_Switcheroo as well as Bumblebee was coming to end of development..

https://github.com/Bumblebee-Project/bbswitch

bbswitch is sliding into no longer maintained. Last proper release was Version 0.8 - 5 December 2013. So are over 4 years out with no maintenance if it works on newer hardware good luck to you particularly if you need something fixed.

Fairly much on muxless VGA_Switcheroo should be as better a bbsswtich unless there is a bug to report. Of course bbsswitch does not work with Mux solutions.

bbsswitich does not know how to handle like hdmi audio correctly but VGA_Switcheroo does.

Also https://nouveau.freedesktop.org/wiki/Optimus/ all the parts from Bumblebee are heading to superseded for the past 4 years. Combination of Prime Offload and VGA_Switcheroo are fairly much replace what the Bumblebee parts use to-do.

[ssorgatem]

Can this be used to switch between 2 discrete GPUs?

[mihau]

I'm hoping this will finally fix the broken HDMI audio on my ThinkPad T430, which is the only thing keeping me from going with nouveau full-time. I'm going to compile a kernel with those patches and find out.

[Vistaus]

https://github.com/Bumblebee-Project/Bumblebee/tree/master/src/switch

bbsswitch comes from Bumblebee do notice here they are using VGA_Switcheroo as well as Bumblebee was coming to end of development..

https://github.com/Bumblebee-Project/bbswitch

bbswitch is sliding into no longer maintained. Last proper release was Version 0.8 - 5 December 2013. So are over 4 years out with no maintenance if it works on newer hardware good luck to you particularly if you need something fixed.

Fairly much on muxless VGA_Switcheroo should be as better a bbsswtich unless there is a bug to report. Of course bbsswitch does not work with Mux solutions.

bbsswitich does not know how to handle like hdmi audio correctly but VGA_Switcheroo does.

Also https://nouveau.freedesktop.org/wiki/Optimus/ all the parts from Bumblebee are heading to superseded for the past 4 years. Combination of Prime Offload and VGA_Switcheroo are fairly much replace what the Bumblebee parts use to-do.

You're right about the releases of bbswitch, but do note that the last commit was last year: https://github.com/Bumblebee-Project...h/tree/develop