On Monday, May 18, 2015 11:06:53 PM Jarod Wilson wrote: > On 5/18/2015 7:06 PM, Rafael J. Wysocki wrote: > > On Monday, May 18, 2015 04:45:28 PM Jarod Wilson wrote: > ... > >>>>>>> On Thu, May 14, 2015 at 03:33:58PM -0400, Jarod Wilson wrote: > >>>>>>>> The HP ZBook 15 and 17 Mobile Workstations, generation 2, up to and > >>>>>>>> including at least BIOS revision 01.07, do not have an ACPI _RMV > >>>>>>>> object > >>>>>>>> associated with their expresscard slots, so acpi-based > >>>>>>>> hotplug-capable > >>>>>>>> slot detection fails. If we fall back to pcie-based detection, the > >>>>>>>> systems > >>>>>>>> work just fine > ... > >> Ah, I forgot some additional details. pciehp_probe() in > >> drivers/pci/hotplug/pciehp_core.c fails on the > >> pciehp_acpi_slot_detection_check() call for the expresscard slot, which > >> is why the base pciehp doesn't bind. DEVICE_ACPI_HANDLE(&dev->dev) in > >> the slot detection check is winding up with a NULL acpi device. > > > > So IMO the bug is that select_detection_mode() assumes that ACPI should be > > used as the PCIe hotplug detection method if it has found at least one > > device that looks like an "ACPI hotplug slot" (Thuderbolt breaks that "logic"). > > > > To be honest, I'm not sure why we need the pciehp_acpi_slot_detection_check() > > in pciehp_probe() at all. It doesn't add any value as far as I can say. > > > > If pciehp_probe() is called at all, we have registered a PCIe port service > > and if this is a "hotplug" service, we wouldn't have registered it if the > > _OSC handshake had not given us contol over native hotplug. > > > > So I wonder if the patch below makes any difference. > > Yeah, that also works, for the most part. You still get spew from > pciehp_acpi_slot_detection_init() saying "Using ACPI for slot > detection.", but in re-reading pciehp_acpi.c in its entirety... I can't > see anything productive that it actually does. I'm of the mind that the > entire file should just be nuked, the path from pciehp_core.c that your > patch alters was the only one that called > pciehp_acpi_slot_detection_check(), and everything else is basically the > dummy probe and fluff, nothing meaningful actually happens. Right, all that is horrible horrible garbage. > I can whip up a follow-up patch that neuters that file entirely in the morning. Well, let me have that pleasure. :-) Anyway, code that is only used in one place should be dropped along with its only user. > At the very least, the "Using ACPI" bit needs to be beaten into submission, > since its not going to be accurate. An updated patch will follow this message. -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- 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
