linux-kernel - Re: 3.8.0-rc4+ - Oops on removing WinTV-HVR-1400 expresscard TV Tuner

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Date:	Fri, 15 Mar 2013 16:48:33 -0600
From:	Bjorn Helgaas <bhelgaas@...gle.com>
To:	Chris Clayton <chris2553@...glemail.com>
Cc:	Martin Mokrejs <mmokrejs@...d.natur.cuni.cz>,
	Yijing Wang <wangyijing@...wei.com>,
	Yijing Wang <wangyijing0307@...il.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
	"Rafael J. Wysocki" <rjw@...k.pl>
Subject: Re: 3.8.0-rc4+ - Oops on removing WinTV-HVR-1400 expresscard TV Tuner

On Tue, Mar 12, 2013 at 4:20 PM, Bjorn Helgaas <bhelgaas@...gle.com> wrote:
> On Sat, Mar 9, 2013 at 2:20 AM, Chris Clayton <chris2553@...glemail.com> wrote:
>> On 03/08/13 22:57, Bjorn Helgaas wrote:

>>> Thanks.  I opened this bug report:
>>> https://bugzilla.kernel.org/show_bug.cgi?id=54981 to keep track of
>>> your logs.

Hi Chris,

The current Linux acpiphp driver doesn't do anything unless it finds
devices with _EJ0 or _RMV methods, and your DSDT has neither.  But I
think that implementation is incorrect because I'm not convinced that
those methods are required in order to do hotplug via ACPI.  For
example, your DSDT *does* have an _L01 method that does notifications
to the root ports.  I suspect that hotplug events on your box generate
an SCI that invokes that method.  Linux basically ignores the
resulting notify events, and I suspect that hotplug works on Windows
because it is paying attention to them.

Can you build a kernel with CONFIG_ACPI_DEBUG=y, do the following, and
attach all the output to the bugzilla?

1) Boot with empty ExpressCard slot (without using "pcie_ports=native")
2) # echo 0x00010004 > /sys/module/acpi/parameters/debug_layer
3) # echo 0x08000004 > /sys/module/acpi/parameters/debug_level
4) # lspci -vv
5) # setpci -s 1c.3 0x42.w
6) # setpci -s 1c.3 0x5a.w
7) # setpci -s 1c.3 0xd8.l
8) Insert ExpressCard
9) # setpci -s 1c.3 0x5a.w
10) # dmesg

Here's what I think we'll see:

- Slot Implemented (bit 8 of XCAP at 0x42) set, indicating a slot is
implemented below this root port
- Hot Plug SCI Enable (bit 30 of MPC at 0xd8) set, indicating that the
root port should generate an SCI whenever a hotplug event is detected
- Presence Detect State (bit 6 of SLTSTS at 0x5a) change from 0 with
the slot empty to 1 with the slot occupied
- pciehp doing nothing (since _OSC didn't grant the OS permission to
use PCIe native hotplug)
- dmesg indication of the SCI, leading to a Bus Check notification to
\_SB.PCI0.RP04, which is the 1c.3 root port leading to the ExpressCard
slot

A Bus Check notification means we're supposed to re-enumerate starting
at that device.  If we *did* re-enumerate, we would find the new
ExpressCard.

Thanks,
  Bjorn
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