[+cc Ashok, Keith] On Thu, Feb 09, 2017 at 05:06:48AM +0100, Lukas Wunner wrote: > On Wed, Feb 08, 2017 at 01:22:56PM -0600, Bjorn Helgaas wrote: > > Bjorn Helgaas (1): > > Revert "PCI: pciehp: Add runtime PM support for PCIe hotplug ports" > > What's the rationale for reverting this? > > You've received patches to fix the issue on both affected machines, > so a revert seems unnecessary: > > https://patchwork.kernel.org/patch/9557113/ > https://patchwork.kernel.org/patch/9562007/ I don't think we've gotten to the root cause of the problem yet, and I don't want to throw in fixes at the last minute without a better understanding of it. PCIe hotplug hardware is not very complicated, it hasn't changed in many years, and at least for the Intel hardware in question, is generally pretty well-tested with Windows. So I want to be careful about asserting that this new piece of hardware is broken. I think pciehp is unnecessarily complicated, and we do have known synchronization issues with it, e.g., [1] [2]. It seems possible that if we poked a little deeper, we would find that the hardware is actually working correctly and the real problem is in pciehp. That's why I've been trying to have a conversation about how we interpret the spec and how we could remove PM and pciehp from the picture and experiment directly with setpci. [1] https://lkml.kernel.org/r/1481317564-18045-1-git-send-email-ashok.raj@xxxxxxxxx [2] https://bugzilla.kernel.org/show_bug.cgi?id=117561
