Changes brightness between discrete and integrated graphics card

[borekb]

I'm on a MacBook Pro 2015 which has two graphics cards and when in a browser and visiting certain websites like messenger.com, the system switches from the integrated Iris graphics card to the discrete one, probably because something GPU-heavy happens there (not sure why FB Messenger would cause that but I see this consistently).

With Brightness installed and enabled, I see a significant change of screen brightness when the GPUs are switched – integrated is the "correct" brightness while switching to a discrete card makes the display very dark.

I tried quitting Brightness and this effect went away.

Note that I don't have any external monitor attached. This effect in fact doesn't exist with external monitor attached as that forces the GPU to be the discrete one so there is no dynamic switching.

Is there any more info I could provide? Thanks.

[baragona]

Good find -- it seems to be a bug where brightness should just not be set at all on a integrated display -- but sometimes it happens anyways, for yet unknown reasons