On Wednesday, December 28, 2016 10:18:16 AM Bjorn Helgaas wrote: > On Wed, Dec 28, 2016 at 12:29:54PM +0100, Lukas Wunner wrote: > > On Tue, Dec 27, 2016 at 05:57:37PM -0600, Bjorn Helgaas wrote: > > > Thanks for the report (https://bugzilla.kernel.org/show_bug.cgi?id=190861) > > > and all the debugging you've done. Below is a revert of the troublesome > > > commit. Can you test it and verify that it also fixes the problem? > > > > > > I assume Mika is looking at this and will have a better solution soon. > > > But if not, I'll queue this up for v4.10. > > > > @Kilian: Are you using the proprietary nvidia driver? If so, > > does the issue go away if you blacklist that driver or use nouveau > > instead? > > > > > > With a bit of googling I found dmesg and lspci output for this model: > > https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1437386 > > > > The keyboard and mouse seem to be PS/2 devices, accessed via I/O ports > > 0x60, 0x64. I assume they're located behind the LPC bridge? > > > > The proprietary nvidia driver has a bug, it locks the legacy PCI VGA > > registers with vga_tryget() but never releases that lock. Intel > > chipsets have a quirk wherein I/O ports are routed to the bus to > > which the legacy PCI VGA registers are locked. So once vga_tryget() > > is called by the nvidia driver, access to the keyboard and mouse is > > routed to bus 01 (on which the Nvidia card resides) and not to bus 00 > > (on which the LPC bridge resides). > > Interesting. A spec reference would be a good addition to whatever > fix is proposed. > > > My theory would be that if you lock the screen, the Nvidia card > > runtime suspends, allowing the root port above it to suspend, > > and then the I/O ports are no longer accessible. > > > > We have a similar issue on dual GPU MacBook Pros: Backlight brightness > > is adjusted by writing to I/O ports of a gmux controller situated below > > the LPC bridge. The nvidia driver locks the legacy VGA registers and > > from that point reads from the I/O ports always return 0xff. Commit > > 4eebd5a4e726 ("apple-gmux: lock iGP IO to protect from vgaarb changes") > > sought to fix it but caused other breakage which remains unfixed so far: > > https://bugzilla.kernel.org/show_bug.cgi?id=105051 > > https://bugzilla.kernel.org/show_bug.cgi?id=88861#c11 > > > > I've always wondered if the Intel chipsets would behave more sensibly > > if the LPC bridge had BARs specifying the I/O regions used by devices > > below it. > > > > Reverting runtime suspend for PCIe ports is not a good solution as it's > > needed for Thunderbolt runtime PM on Macs. > > The choices are: > > 1) Fix the regression and preserve runtime PM for PCIe ports > 2) Fix the regression by reverting runtime PM for PCIe ports > > Obviously we hope for 1). Preserving runtime PM without fixing the > regression isn't even on the list. I know this is Linux 101, so I > apologize for restating the obvious. There is a couple of obvious things we can do other than reverting, though. Like for example changing the cutoff date we have in there to cover the Kilian's system. Thanks, Rafael -- 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
