[PATCH v2] PCI: dwc: Fix resume failure if no EP is connected at some platforms

[Hongxing Zhu]

> -----Original Message-----
> From: Krzysztof Wilczy¨½ski <kw at linux.com>
> Sent: 2024Äê11ÔÂ7ÈÕ 15:20
> To: Hongxing Zhu <hongxing.zhu at nxp.com>
> Cc: Bjorn Helgaas <helgaas at kernel.org>; bhelgaas at google.com;
> lorenzo.pieralisi at arm.com; Frank Li <frank.li at nxp.com>; mani at kernel.org;
> linux-pci at vger.kernel.org; linux-arm-kernel at lists.infradead.org;
> linux-kernel at vger.kernel.org; kernel at pengutronix.de; imx at lists.linux.dev
> Subject: Re: [PATCH v2] PCI: dwc: Fix resume failure if no EP is connected at
> some platforms
> 
> Hello,
> 
> > > But I don't think you responded to the race question.  What happens
> here?
> > >
> > >   if (dw_pcie_get_ltssm(pci) > DW_PCIE_LTSSM_DETECT_ACT) {
> > >     --> link goes down here <--
> > >     pci->pp.ops->pme_turn_off(&pci->pp);
> > >
> > > You decide the LTSSM is active and the link is up.  Then the link goes
> down.
> > > Then you send PME_Turn_off.  Now what?
> > >
> > > If it's safe to try to send PME_Turn_off regardless of whether the
> > > link is up or down, there would be no need to test the LTSSM state.
> > I made a local tests on i.MX95/i.MX8QM/i.MX8MP/i.MX8MM/i.MX8MQ,
> and
> > confirm that it's safe to send PME_TURN_OFF although the link is down.
> > You're right. It's no need to test LTSSM state here.
> > So do the L2 poll listed above after PME_TURN_OFF is sent.
> >
> > Since the 6.13 merge window is almost closed.
> > How about I prepare another Fix patch to do the following items for
> > incoming 6.14?
> > - Before sending PME_TURN_OFF, don't test the LTSSM stat.
> > - Remove the L2 stat poll, after sending PME_TURN_OFF.
> 
> If the changes aren't too involved, then I would rather fix it or drop the not
> needed code now, before we sent the Pull Request.
> 
> So, feel free to sent a small patch against the current branch, or simply let me
> know how do you wish the current code to be changed, so I can do it against
> the current branch.
Thanks for your kindly reminder.
This clean up small patch is on the way.

Best Regards
Richard Zhu
> 
> Thank you!
> 
> 	Krzysztof