Messages in this thread | | | Date | Mon, 3 Apr 2023 12:02:21 +0800 | From | Wu Zongyong <> | Subject | Re: [RFC PATCH] PCI: avoid SBR for NVIDIA T4 |
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On Fri, Mar 31, 2023 at 10:11:15AM +0800, Wu Zongyong wrote: > On Thu, Mar 30, 2023 at 10:49:26AM -0500, Bjorn Helgaas wrote: > > On Thu, Mar 30, 2023 at 10:10:16AM +0800, Wu Zongyong wrote: > > > On Wed, Mar 29, 2023 at 12:05:15PM -0500, Bjorn Helgaas wrote: > > > > On Wed, Mar 29, 2023 at 07:58:45PM +0800, Wu Zongyong wrote: > > > > > Secondary bus reset will fail if NVIDIA T4 card is direct attached to a > > > > > root port. > > > > > > > > Is this only a problem when direct attached to a Root Port? Why would > > > > that be? If it's *not* related to being directly under a Root Port, > > > > don't mention that at all. > > > > > > Yes, this problem occurs only when the T4 card is direct attached to a > > > Root Port. > > > I have test it with a T4 card attached to a PCIe Switch or a PCI Bridge, > > > and it works well. > > > > From an electrical and protocol point of view, the device should not > > be able to tell the difference, so Lukas' suggestion that it may be > > related to reset delays seems very pertinent. > I will test it with the commits mentioned above. > But it may take some time since it is not easy to replace kernel in our > environment.
I have tested it with Lukas' suggestion and it didn't work for T4 cards.
My base kernel is v5.10, and I cherry-picked the following patches:
730643d33e2d ("PCI/PM: Resume subordinate bus in bus type callbacks") 8ef0217227b4 ("PCI/PM: Observe reset delay irrespective of bridge_d3") ac91e6980563 ("PCI: Unify delay handling for reset and resume")
Any other necessary patches I should apply?
> > > > Bjorn
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