From: Vidya Sagar <vidyas@nvidia.com>
To: Sinan Kaya <okaya@kernel.org>, Thierry Reding <treding@nvidia.com>
Cc: <bhelgaas@google.com>, <lorenzo.pieralisi@arm.com>,
<jonathanh@nvidia.com>, <linux-tegra@vger.kernel.org>,
<linux-pci@vger.kernel.org>, <kthota@nvidia.com>,
<mmaddireddy@nvidia.com>, <sagar.tv@gmail.com>
Subject: Re: [PATCH] PCI: Add CRS timeout for pci_device_is_present()
Date: Tue, 15 Oct 2019 17:04:01 +0530 [thread overview]
Message-ID: <ddb0b314-7f8b-0714-773d-41c3b95288a9@nvidia.com> (raw)
In-Reply-To: <ce411d27-5b92-8dae-fccd-73c63aa30f1c@kernel.org>
On 10/15/2019 1:51 AM, Sinan Kaya wrote:
> On 10/14/2019 1:20 AM, Thierry Reding wrote:
>> I think this makes sense, so:
>>
>> Reviewed-by: Thierry Reding <treding@nvidia.com>
>>
>> However, it looks like Sinan has researched this extensively in the past
>> and gave a presentation on this at Plumbers in 2017:
>>
>> https://blog.linuxplumbersconf.org/2017/ocw/system/presentations/4732/original/crs.pdf
>>
>> Adding Sinan to see if he has any concerns about this, since resume time
>> is explicitly mentioned in the above slides.
>
>
> Thanks for including me. Let me catch up here.
>
> pci_dev_wait() is supposed to handle this case via pci_pm_reset().
>
> /**
> * pci_pm_reset - Put device into PCI_D3 and back into PCI_D0.
> * @dev: Device to reset.
> * @probe: If set, only check if the device can be reset this way.
> */
>
> Do you know if your execution path hits this function? We might have
> missed a use case.
>
Nope. It doesn't.
Following is the stack dump showing how pci_update_current_state() is called in resume() path.
And pci_device_is_present() is called from inside pci_update_current_state() API.
My understanding is that pci_device_is_present() is the API we hit first in the resume() path
for any PCIe device.
[ 36.380726] Call trace:
[ 36.383270] dump_backtrace+0x0/0x158
[ 36.386802] show_stack+0x14/0x20
[ 36.389749] dump_stack+0xb0/0xf8
[ 36.393451] pci_update_current_state+0x58/0xe0
[ 36.398178] pci_power_up+0x60/0x70
[ 36.401672] pci_pm_resume_noirq+0x6c/0x130
[ 36.405669] dpm_run_callback.isra.16+0x20/0x70
[ 36.410248] device_resume_noirq+0x120/0x238
[ 36.414364] async_resume_noirq+0x24/0x58
[ 36.418364] async_run_entry_fn+0x40/0x148
[ 36.422418] process_one_work+0x1e8/0x360
[ 36.426525] worker_thread+0x40/0x488
[ 36.430201] kthread+0x118/0x120
[ 36.433843] ret_from_fork+0x10/0x1c
Also, I don't see pci_pm_reset() getting called in resume() path at all.
Thanks,
Vidya Sagar
next prev parent reply other threads:[~2019-10-15 11:34 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-05 18:21 [PATCH] PCI: Add CRS timeout for pci_device_is_present() Vidya Sagar
2019-10-14 8:20 ` Thierry Reding
2019-10-14 20:21 ` Sinan Kaya
2019-10-15 9:30 ` Thierry Reding
2019-10-15 11:10 ` Sinan Kaya
2019-10-15 12:14 ` Vidya Sagar
[not found] ` <afa16546-e63d-6eba-8be0-8e52339cd100@nvidia.com>
2019-10-25 11:58 ` Vidya Sagar
2019-10-26 13:59 ` Sinan Kaya
2019-11-04 11:43 ` Vidya Sagar
2019-11-04 16:52 ` Lorenzo Pieralisi
2019-11-04 17:39 ` Bjorn Helgaas
2019-11-05 10:55 ` Rafael J. Wysocki
2019-11-06 16:41 ` Bjorn Helgaas
2019-11-11 6:01 ` Vidya Sagar
2019-11-11 22:32 ` Bjorn Helgaas
2019-11-12 12:59 ` Thierry Reding
2019-11-12 14:21 ` Bjorn Helgaas
2019-11-12 17:59 ` Vidya Sagar
2019-11-12 18:58 ` Bjorn Helgaas
2019-11-13 5:39 ` Vidya Sagar
2019-11-13 11:20 ` Thierry Reding
2019-11-14 18:36 ` Bjorn Helgaas
2019-11-15 10:04 ` Vidya Sagar
2019-11-15 22:36 ` Bjorn Helgaas
2019-11-18 15:18 ` Vidya Sagar
2019-11-12 17:59 ` Vidya Sagar
2019-10-15 12:03 ` Vidya Sagar
2019-10-15 11:34 ` Vidya Sagar [this message]
2019-10-14 10:45 ` Andrew Murray
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