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@xxxxxxxxxx
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