On Thu, Sep 13, 2018 at 10:15 PM Rafael J. Wysocki <r...@rjwysocki.net> wrote: > > On Thursday, September 13, 2018 12:03:36 PM CEST James Wang wrote: > > This is a multi-part message in MIME format. > > --------------F5519E624D0AD1E3F7DDA019 > > Content-Type: text/plain; charset=utf-8 > > Content-Transfer-Encoding: 8bit > > > > > > > > On 09/11/2018 02:15 PM, Takashi Iwai wrote: > > > On Tue, 11 Sep 2018 14:11:30 +0200, > > > James Wang wrote: > > >> I did try it from kernel : head > > > OK, then the bug is present with 4.19-rc2, at least. > > > Please check my test kernel later (it's still being built). > > Hi folks, I attach two log about 4.19-rc3 and 4.19-rc3+Rafeal suggestion. > > OK, no difference AFAICS. > > This means that the commit turned up by bisection simply uncovered an existing > ordering issue, apparently between an IOMMU and its client (ie. it appears > that > the client is shut down after the IOMMU). > > This isn't limited to shutdown and you'd see the same issue on system-wide > suspend/resume (in fact, the Pingfan Liu's patches make shutdown use the > same device list that is used for system-wide PM). > > One way to mitigate such issues is to add a device link between the two > devices in question to enforce the correct suspend/resume/shutdown ordering > between them. > I found the iommu was at " 0000:00:00.2", while ohci-pci is at 0000:00:13.1. Hence ohci-pci should be shutdown before iommu. Not familiar with AMD's iommu code, but I think there is no shutdown interface exported to drivers/base. It is shutdown by platform code in arch/x86. So I think there should be someone teared down the iotbl, e.g. by invalidating pages, before the shutdown of ohci-pci. I wonder whether adding a device link can fix this bug or not. (Forgive me if I made a mistake, since I am ignorant in this field)
Thanks, Pingfan
