On Wed, Jun 01, 2016 at 06:51:51PM +0200, Peter Wu wrote: > On Tue, May 31, 2016 at 02:20:26PM +0200, Lukas Wunner wrote: > > On Mon, May 30, 2016 at 06:13:51PM +0200, Peter Wu wrote: > > > Do you have any suggestions for the case where the pcieport driver > > > refuses to put the bridge in D3 (because the BIOS is too old)? In that > > > case the nouveau driver needs to fallback to the DSM method (but not > > > when runtime PM is deliberately disabled by writing control=on). > > > > The BIOS cut-off date is meant to avoid issues when suspending ports > > on older chipsets. However if the port is used for an Optimus GPU > > and we can clearly identify that, and there's a _PR3 method provided, > > it's probably safe to say that the port is *intended* to be suspended. > > > > So you may want to consider amending pci_bridge_d3_possible() to > > allow D3 for such ports regardless of the BIOS date, as I've done > > for Thunderbolt in this commit: > > https://github.com/l1k/linux/commit/3cb8549cd4e5 > > Then we have heuristics based on BIOS year, on whether it is TB or not, > and next to it whether it is an Optimus laptop? Maybe the PCI core needs > to export a function that allows drivers to override the detection if > this becomes more common. Well I consider the TB and Optimus whitelisting as a stop-gap until the BIOS date is lowered. Rafael wrote: Some time around when machines with Windows 10 started to ship should be relatively safe. I guess we can just pick a reasonable date in the initial patch and then try to move it back to the past subsequently and see if that breaks things for anyone. Source: http://permalink.gmane.org/gmane.linux.power-management.general/75133 > > > Not sure how to uniquely identify such ports though. Perhaps check > > if there's a device in slot 0 below the port which has > > (pdev->class >> 16) == PCI_BASE_CLASS_DISPLAY && > > (pdev->vendor == PCI_VENDOR_ID_NVIDIA || > > pdev->vendor == PCI_VENDOR_ID_ATI) > > Seems fragile, there are desktop setups satisfying this match. Of course, I didn't mean this to be used as is, you'd have to augment this with checks e.g. for presence of _PR3 and (if possible) Optimus, but I'm not familiar enough with Optimus to write down working code for it, I'm only familiar with apple-gmux switching. Best regards, Lukas -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
