linux-kernel - Re: [PATCH v5 0/5] Verify devices transition from D3cold to D0

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Message-ID: <a1dafdb9-1480-480a-97f1-b43367d883fb@kernel.org>
Date: Wed, 4 Dec 2024 21:44:05 -0600
From: Mario Limonciello <superm1@...nel.org>
To: Bjorn Helgaas <helgaas@...nel.org>
Cc: Bjorn Helgaas <bhelgaas@...gle.com>,
 "open list : PCI SUBSYSTEM" <linux-pci@...r.kernel.org>,
 open list <linux-kernel@...r.kernel.org>,
 "open list : USB XHCI DRIVER" <linux-usb@...r.kernel.org>,
 Daniel Drake <drake@...lessos.org>, Gary Li <Gary.Li@....com>,
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
 Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
 Mathias Nyman <mathias.nyman@...el.com>,
 Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: Re: [PATCH v5 0/5] Verify devices transition from D3cold to D0

On 12/4/2024 17:45, Bjorn Helgaas wrote:
> On Wed, Dec 04, 2024 at 11:30:51AM -0600, Mario Limonciello wrote:
>> On 8/23/2024 10:40, Mario Limonciello wrote:
>>> From: Mario Limonciello <mario.limonciello@....com>
>>>
>>> Gary has reported that when a dock is plugged into a system at the same
>>> time the autosuspend delay has tripped that the USB4 stack malfunctions.
>>>
>>> Messages show up like this:
>>>
>>> ```
>>> thunderbolt 0000:e5:00.6: ring_interrupt_active: interrupt for TX ring 0 is already enabled
>>> ```
>>>
>>> Furthermore the USB4 router is non-functional at this point.
>>>
>>> Those messages happen because the device is still in D3cold at the time
>>> that the PCI core handed control back to the USB4 connection manager
>>> (thunderbolt).
>>>
>>> The issue is that it takes time for a device to enter D3cold and do a
>>> conventional reset, and then more time for it to exit D3cold.
>>>
>>> This appears not to be a new problem; previously there were very similar
>>> reports from Ryzen XHCI controllers.  Quirks were added for those.
>>> Furthermore; adding extra logging it's apparent that other PCI devices
>>> in the system can take more than 10ms to recover from D3cold as well.
>>>
>>> This series add a wait into pci_power_up() specifically for D3cold exit and
>>> then drops the quirks that were previously used for the Ryzen XHCI controllers.
>>>
>>> Mario Limonciello (5):
>>>     PCI: Use an enum for reset type in pci_dev_wait()
>>>     PCI: Check PCI_PM_CTRL instead of PCI_COMMAND in pci_dev_wait()
>>>     PCI: Verify functions currently in D3cold have entered D0
>>>     PCI: Allow Ryzen XHCI controllers into D3cold and drop delays
>>>     PCI: Drop Radeon quirk for Macbook Pro 8.2
>>>
>>>    drivers/pci/pci-driver.c    |  2 +-
>>>    drivers/pci/pci.c           | 70 +++++++++++++++++++++++++++----------
>>>    drivers/pci/pci.h           | 13 ++++++-
>>>    drivers/pci/pcie/dpc.c      |  2 +-
>>>    drivers/pci/quirks.c        | 25 -------------
>>>    drivers/usb/host/xhci-pci.c | 11 ------
>>>    6 files changed, 66 insertions(+), 57 deletions(-)
>>
>> Bjorn,
>>
>> This series has stalled a while.
>>
>> Mika and I went back and forth and I think are generally in agreement so I
>> think it's waiting on your feedback.
>>
>> Can you take another look?
>>
>> The alternative is to add some more piles of quirks, but I'm hoping that we
>> can go this direction and drop a bunch of the old ones instead.
>>
>> LMK if you want me to rebase it on 6.13-rc1 and resend a v6.
> 
> I'm still stuck on patch 2/5 because I'm not aware of any spec
> language about polling PCI_PM_CTRL to wait for a power state
> transition, so it seems really ad hoc.

I'm not really sure how to overcome this.  If I rebase everything I'll 
give specs another read through in case I missed anything, but I suspect 
you know these specs better than anyoe on this list.

Is it worth raising this to PCI-SIG to discuss?
Did you perhaps already do that?

> 
> If you do rebase to v6.13-rc1, in the 2/5 commit log,
> s/evices/devices/.
> 
> I guess that whole patch and commit log needs updating since the RRS
> code was added to pci_dev_wait() in the interim, so the "device that
> has gone through a reset may return a value in PCI_COMMAND but that
> doesn't mean it's finished transitioning to D0" doesn't directly apply
> anymore.
> 
> Bjorn