Date:	Mon, 28 Jan 2013 11:56:37 +0100
From:	Martin Mokrejs <mmokrejs@...d.natur.cuni.cz>
To:	Chris Clayton <chris2553@...glemail.com>
CC:	Yijing Wang <wangyijing@...wei.com>,
	Yijing Wang <wangyijing0307@...il.com>,
	linux-media@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	linux-pci@...r.kernel.org
Subject: Re: 3.8.0-rc4+ - Oops on removing WinTV-HVR-1400 expresscard TV Tuner



Chris Clayton wrote:
> Hi Yijing,
> 
> On 01/28/13 02:40, Yijing Wang wrote:
>> Hi Chris,
>>     Sorry for the delay reply. It seems like my reply last night was missed.
>>
>>  From the sysinfo you provide, there are no pcie port devices under /sys/bus/pci_express/devices.
>> Maybe because there are some problems with _OSC in your laptop, so pcie port driver won't create pcie port device
>> for hotplug, aer and so on.
>>
>> Maybe you can add boot parameter "pcie_ports=native" and reboot your laptop.
>> Then use #modprobe pciehp pciehp_force=1 pciehp_debug=1 to load pciehp modules.
>> After above actions, enter /sys/bus/pci_express/devices/ directory and /sys/bus/pci/slots/
>> Some slots and pcie port devices should be there now.
>>
> Sorry, I've tried your suggestion, but the two directories are still empty.
> 
> I verified the test environment as follows:
> 
> [chris:~]$ uname -a
> Linux laptop 3.7.4 #15 SMP PREEMPT Mon Jan 28 09:43:57 GMT 2013 i686 GNU/Linux
> [chris:~]$ grep acpiphp /boot/System.map-3.7.4
> [chris:~]$ modinfo acpiphp
> modinfo: ERROR: Module acpiphp not found.
> [chris:~]$ modinfo pciehp
> filename:       /lib/modules/3.7.4/kernel/drivers/pci/hotplug/pciehp.ko
> license:        GPL
> description:    PCI Express Hot Plug Controller Driver
> author:         Dan Zink <dan.zink@...paq.com>, Greg Kroah-Hartman <greg@...ah.com>, Dely Sy <dely.l.sy@...el.com>
> depends:
> intree:         Y
> vermagic:       3.7.4 SMP preempt mod_unload CORE2
> parm:           pciehp_detect_mode:Slot detection mode: pcie, acpi, auto
>   pcie          - Use PCIe based slot detection
>   acpi          - Use ACPI for slot detection
>   auto(default) - Auto select mode. Use acpi option if duplicate
>                   slot ids are found. Otherwise, use pcie option
>  (charp)
> parm:           pciehp_debug:Debugging mode enabled or not (bool)
> parm:           pciehp_poll_mode:Using polling mechanism for hot-plug events or not (bool)
> parm:           pciehp_poll_time:Polling mechanism frequency, in seconds (int)
> parm:           pciehp_force:Force pciehp, even if OSHP is missing (bool)
> [chris:~]$ cat /proc/cmdline
> root=/dev/sda5 pciehp_ports=native ro resume=/dev/sda6
> [chris:~]$ sudo modprobe pciehp pciehp_force=1 pciehp_debug=1
> [chris:~]$ lsmod
> Module                  Size  Used by
> pciehp                 19907  0
> [...]
> 
> You will notice that the kernel I have used is 3.7.4. I hope that's a suitable kernel for your tests. I've moved away from the 3.8 development kernel onto one that's stable and on which Martin has identified a solution. I see Greg KH released 3.7.5 yesterday and it includes a pciehp change. I'll upgrade to that, run the tests again and report back.
> 
> One question - should I include the (acpi) pci_slot driver in the kernel build or does pciehp populate the directories without pci_slot?

Hi Chris,
  I am not a kernel developer but from the other threads at linux-pci I gathered there are in some
scenarios problems with improper loading of the hotplug modules. Therefore, the patches floating
now around are to disable hotplug module availability. Therefore, I suggested you to try only
only static kernel support for hotplug. That way you don't hit the issue. That is for sure not
addressed in 3.7.5, seems that it is probably in -next.
Martin

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