On Mon, Oct 9, 2017 at 11:45 AM, Christian König <ckoenig.leichtzumerken@xxxxxxxxx> wrote: > Am 09.10.2017 um 16:41 schrieb Ilia Mirkin: >> >> Hello, >> >> As a bit of background, all NVIDIA GPUs since GT215 have an audio >> subfunction for HDMI(/DP) audio to be sent to the sink. This generally >> works. >> >> However some, especially laptop, devices come up with that function >> disabled. We have a quirk to enable it when coming back from runpm, >> but that doesn't help the init case. Basically we have to write a bit >> to the PCI config space: >> >> >> https://github.com/torvalds/linux/blob/v4.12/drivers/gpu/drm/nouveau/nouveau_drm.c#L783 >> >> (MMIO 0x88000 is an alias for the PCI config space) >> >> This works for runtime pm resume, since the device was originally >> there and we just have to make sure the underlying device agrees with >> it, but when it's missing on boot, we have to convince linux that it >> exists, bind a driver, etc. >> >> What's the best way of going about doing that? > > > Sounds similar to my work about resizing BARs. > > I would just try to enable the device and then trigger a rescan of the BUS > where it is attached (similar to echo 1 > > /sys/bus/pci/devices/$pci_id_of_your_bus/rescan). > > There is certainly a function in the PCI subsystem you just need to call for > that. I'm not exactly familiar with the pci subsystem. I know that hotplug is a thing, at least in theory. I figured it'd be something related to that, since this is in essence a random device appearing on the bus after the initial scan. Is a bus rescan safe on a fully initialized system? Either way, some specific functions to call or look at would be great. Cheers, -ilia _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
