Hi, On Tue, Feb 15, 2022 at 4:41 PM Brian Norris <briannorris@xxxxxxxxxxxx> wrote: > > On Tue, Feb 15, 2022 at 3:46 PM Doug Anderson <dianders@xxxxxxxxxxxx> wrote: > > On Tue, Feb 15, 2022 at 2:52 PM Brian Norris <briannorris@xxxxxxxxxxxx> wrote: > > > It still makes me wonder what the point > > > of the /dev/drm_dp_aux<N> interface is though, because it seems like > > > you're pretty much destined to not have reliable operation through > > > that means. > > > > I can't say I have tons of history for those files. I seem to recall > > maybe someone using them to have userspace tweak the embedded > > backlight on some external DP connected panels? I think we also might > > use it in Chrome OS to update the firmware of panels (dunno if > > internal or external) in some cases too? I suspect that it works OK > > for certain situations but it's really not going to work in all > > cases... > > Yes, I believe I'm only submitting patches like this because fwupd > apparently likes to indiscriminately whack at dpaux devices: > https://github.com/fwupd/fwupd/tree/main/plugins/synaptics-mst#kernel-dp-aux-interface > > That seems like a bad idea. > > (We've already disabled that plugin on these systems, but it seems > wise not to leave the stumbling block here for the next time.) Yeah, it doesn't seem great. I guess it's _slightly_ less bad since it's for an external device. As I understand it, they never really turn off in the same way. It still feels like letting userspace indiscriminately whack at DP AUX registers isn't a great idea, though.
