On Mon, Feb 19, 2018 at 9:54 AM, Daniel Vetter <dan...@ffwll.ch> wrote: > On Mon, Feb 19, 2018 at 03:47:42PM +0100, Lukas Wunner wrote: >> On Mon, Feb 19, 2018 at 03:05:53PM +0100, Daniel Vetter wrote: >> > On Mon, Feb 19, 2018 at 12:58:17PM +0100, Lukas Wunner wrote: >> > > On Mon, Feb 19, 2018 at 12:34:43PM +0100, Daniel Vetter wrote: >> > > > Well, userspace expects hotplug events, even when we runtime suspend >> > > > stuff. Hence waking shit up with polling. Imo ignoring hotplug events >> > > > is a >> > > > pretty serious policy decision which is ok in the context of >> > > > vga_switcheroo, but not really as an automatic thing. E.g. usb also >> > > > wakes >> > > > up if you plug something in, even with all the runtime pm stuff >> > > > enabled. >> > > > Same for sata and everything else. >> > > >> > > On the MacBook Pro, the HPD pin of external DP and HDMI ports goes into >> > > the gmux controller, which sends an interrupt on hotplug even if the GPU >> > > is powered down. >> > > >> > > Apparently Optimus has a similar functionality, cf. 3a6536c51d5d. >> > >> > Yeah, for vga_switcheroo and gmux setups shutting down polling explicitly >> > makes sense. I think ideally we'd stop polling in the gmux handler somehow >> > (maybe by dropping the relevant DRM_CONNECTOR_POLL flags, or outright >> > stopping it all). But not when runtime suspending the entire gpu (e.g. >> > idle system that shuts down the screen and everything, before it decides >> > a few minutes later to do a full system suspend). >> >> nouveau, radeon and amdgpu currently use runtime PM *only* on hybrid >> graphics laptops. >> >> Should the drivers later be extended to also use runtime PM in other >> scenarios (desktop machines, eGPUs), they can easily detect whether >> to disable polling on runtime suspend by calling apple_gmux_present() >> on Macs or the equivalent for Optimus/ATPX. > > Ah, then I think the current solution is ok (if not entirely clean imo, > but that can be fixed up whenever it hurts). Implementing runtime pm for > other cases is up to the driver authors really (probably more pressing > when the gpu is on the same SoC).
On our APUs, we support fairly fine grained powergating so this mostly happens auto-magically in hw; no need for runtimepm. We haven't supported native analog encoders in last 3 or 4 generations of display hw, so polling is not much of an issue going forward. On most integrated platforms (e.g., laptops and all-in-ones), digital hotplug is handled by the platform (we get an ACPI ATIF notification) so we can wake the dGPU. Alex > -Daniel > >> >> Thanks, >> >> Lukas >> _______________________________________________ >> dri-devel mailing list >> dri-devel@lists.freedesktop.org >> https://lists.freedesktop.org/mailman/listinfo/dri-devel > > -- > Daniel Vetter > Software Engineer, Intel Corporation > http://blog.ffwll.ch > _______________________________________________ > dri-devel mailing list > dri-devel@lists.freedesktop.org > https://lists.freedesktop.org/mailman/listinfo/dri-devel _______________________________________________ dri-devel mailing list dri-devel@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/dri-devel
