Messages in this thread | | | Date | Mon, 18 May 2015 23:06:53 -0400 | From | Jarod Wilson <> | Subject | Re: [PATCH] pci/hotplug: work-around for missing _RMV on HP ZBook G2 |
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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. I can whip up a follow-up patch that neuters that file entirely in the morning. At the very least, the "Using ACPI" bit needs to be beaten into submission, since its not going to be accurate.
-- Jarod Wilson jarod@redhat.com
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