[PATCH v6 0/4] PCI: Add support for resetting the Root Ports in a platform specific way

[Manivannan Sadhasivam]

On Wed, Mar 11, 2026 at 11:59:37AM +0100, Niklas Cassel wrote:
> On Tue, Mar 10, 2026 at 07:07:39PM +0530, Manivannan Sadhasivam wrote:
> > > 
> > > I tested your patch series + your suggested change above, and after a:
> > > 
> > > ## On EP side:
> > > # echo 0 > /sys/kernel/config/pci_ep/controllers/a40000000.pcie-ep/start && \
> > >   sleep 0.1 && echo 1 > /sys/kernel/config/pci_ep/controllers/a40000000.pcie-ep/start
> > > 
> > > Instead of:
> > > 
> > > # FAILED: 1 / 16 tests passed.
> > > 
> > > I now get:
> > > # FAILED: 7 / 16 tests passed.
> > > 
> > > Test cases 1-7 now passes (the test cases related to BARs),
> > > all other test cases still fail:
> 
> (snip)
> 
> > I guess what is going wrong here is that you might be rebooting the device
> > *after* restoring the config space in 'slot_reset()' callback. So all the
> > previous config space contents would be lost and the device would've started
> > afresh.
> 
> I'm confused.
> 
> # echo 0 > /sys/kernel/config/pci_ep/controllers/a40000000.pcie-ep/start && \
>   sleep 0.1 && echo 1 > /sys/kernel/config/pci_ep/controllers/a40000000.pcie-ep/start
> 
> Will not reboot the device.
> 
> 
> > 
> > I don't think we can restore the config space after rebooting the EP device,
> > because host has no idea about it. It can only restore the content after
> > recovering the device through platform specific means.
> 
> Am I missing something, or why are we talking about rebooting the device?
> 

Sorry, I just went with reboot scenario since I remember you referring to it in
the thread. But I must admit that I didn't read your repro steps where you just
write to the 'start' parameter.

But I did test with toggling the LTSSM alone on the EP and was able to execute
the test successfully on the host. So I'm not entirely sure what is going wrong
on yours.

I need to look into it more in detail, but I do not want to block the series
from getting merged due to this.

- Mani

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