linux-kernel - Re: Add option to passively listen for PCIE hotplug events

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Date:	Tue, 04 Nov 2008 16:22:21 +0000
From:	Alan Jenkins <alan-jenkins@...fmail.co.uk>
To:	Matthew Garrett <mjg59@...f.ucam.org>
CC:	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: Add option to passively listen for PCIE hotplug events

Matthew Garrett wrote:
> On Tue, Nov 04, 2008 at 03:44:23PM +0000, Alan Jenkins wrote:
>
>   
>> I instrumented all the delays I could find. hpc_check_lnk_status() was
>> the only one that came up.  1000ms delay per call, and I get 6 such delays.
>>     
>
> Ok, which is getting called from pciehp_enable_slot(). I'm not quite 
> clear on why this is being called 6 times - any chance you can put a 
> dump_stack() in there? Some are probably directly from the resume code. 
> This confuses me a little, since there's a check for whether there's a 
> card in the slot first. If that fails, pciehp_enable_slot() isn't 
> called. If it succeeds, pciehp_enable_slot checks whether the slot is 
> already powered up. If it is, it bails before doing the link setup. So 
> something funny is going on here, since on the Eee I'd expect those 
> slots to either be empty or already powered up.
>
>   
[ 258.344326] ACPI: Waking up from system sleep state S3

A
[ 259.856649] [<e0064b11>] hpc_check_lnk_status+0x107/0x1ba [pciehp]
[ 259.856649] [<e0062eaa>] pciehp_enable_slot+0x19d/0x2c9 [pciehp]
[ 259.856649] [<e00630b5>] pciehp_power_thread+0x96/0xcd [pciehp]
[ 259.856649] [<e006301f>] pciehp_power_thread+0x0/0xcd [pciehp]
[ 259.856649] [<c01269e6>] run_workqueue+0x62/0xc9
...

B
[ 260.860020] [<e0064b11>] hpc_check_lnk_status+0x107/0x1ba [pciehp]
[ 260.860020] [<e0062eaa>] pciehp_enable_slot+0x19d/0x2c9 [pciehp]
[ 260.860020] [<c01c2270>] resume_iter+0x0/0x25
[ 260.860020] [<e0064ded>] hpc_get_adapter_status+0x26/0x65 [pciehp]
[ 260.860020] [<c01c2270>] resume_iter+0x0/0x25
[ 260.860020] [<e0062287>] pciehp_resume+0xce/0xde [pciehp]
[ 260.860020] [<c01c2292>] resume_iter+0x22/0x25
[ 260.860020] [<c02054fa>] device_for_each_child+0x1a/0x3b
[ 260.860020] [<c01bf003>] pci_legacy_resume+0x15/0x16
[ 260.860020] [<c020960f>] pm_op+0x52/0xac
[ 260.860020] [<c0209bd5>] device_resume+0x7d/0x2d2
[ 260.860020] [<c0135c91>] suspend_devices_and_enter+0xc7/0xfb
...

[ 263.393352] A

[ 264.396686] B

[ 265.466684] B

[ 266.470019] B

And there are two more during boot (see below), I'd like them to go away 
too please :).

[ 5.370046] [<e0064b11>] hpc_check_lnk_status+0x107/0x1ba [pciehp]
[ 5.370046] [<e0062eaa>] pciehp_enable_slot+0x19d/0x2c9 [pciehp]
[ 5.370046] [<e0064ded>] hpc_get_adapter_status+0x26/0x65 [pciehp]
[ 5.370046] [<e00629b8>] pciehp_probe+0x3b2/0x3ee [pciehp]
[ 5.370046] [<c0191e61>] sysfs_do_create_link+0x97/0xd7
[ 5.370046] [<c01c276d>] pcie_port_probe_service+0x29/0x63
[ 5.370046] [<c020759b>] driver_probe_device+0xa1/0x117
[ 5.370046] [<c020765a>] __driver_attach+0x49/0x67
[ 5.370046] [<c0206df8>] bus_for_each_dev+0x35/0x56
[ 5.370046] [<c020744a>] driver_attach+0x11/0x13
[ 5.370046] [<c0207611>] __driver_attach+0x0/0x67
[ 5.370046] [<c020713f>] bus_add_driver+0x91/0x192
[ 5.370046] [<c02077b1>] driver_register+0x6d/0xc2
[ 5.370046] [<c0191561>] sysfs_addrm_finish+0x13/0x16f
[ 5.370046] [<e0033000>] pcied_init+0x0/0x5c [pciehp]
[ 5.370046] [<e003300b>] pcied_init+0xb/0x5c [pciehp]

Thanks
Alan


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