> -----Original Message-----
> From: Bjorn Helgaas <helgaas@xxxxxxxxxx>
> Sent: 2024年11月6日 7:35
> To: Hongxing Zhu <hongxing.zhu@xxxxxxx>
> Cc: kwilczynski@xxxxxxxxxx; bhelgaas@xxxxxxxxxx;
> lorenzo.pieralisi@xxxxxxx; Frank Li <frank.li@xxxxxxx>; mani@xxxxxxxxxx;
> linux-pci@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx; imx@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v2] PCI: dwc: Fix resume failure if no EP is connected at
> some platforms
>
> On Mon, Jul 22, 2024 at 02:15:13PM +0800, Richard Zhu wrote:
> > The dw_pcie_suspend_noirq() function currently returns success
> > directly if no endpoint (EP) device is connected. However, on some
> > platforms, power loss occurs during suspend, causing dw_resume() to do
> nothing in this case.
> > This results in a system halt because the DWC controller is not
> > initialized after power-on during resume.
> >
> > Change call to deinit() in suspend and init() at resume regardless of
> > whether there are EP device connections or not. It is not harmful to
> > perform deinit() and init() again for the no power-off case, and it
> > keeps the code simple and consistent in logic.
> > ...
>
> > - ret = read_poll_timeout(dw_pcie_get_ltssm, val, val ==
> DW_PCIE_LTSSM_L2_IDLE,
> > - PCIE_PME_TO_L2_TIMEOUT_US/10,
> > - PCIE_PME_TO_L2_TIMEOUT_US, false, pci);
> > - if (ret) {
> > - dev_err(pci->dev, "Timeout waiting for L2 entry! LTSSM: 0x%x\n",
> val);
> > - return ret;
> > + ret = read_poll_timeout(dw_pcie_get_ltssm, val, val ==
> DW_PCIE_LTSSM_L2_IDLE,
> > + PCIE_PME_TO_L2_TIMEOUT_US/10,
> > + PCIE_PME_TO_L2_TIMEOUT_US, false, pci);
> > + if (ret) {
> > + dev_err(pci->dev, "Timeout waiting for L2 entry! LTSSM:
> 0x%x\n", val);
> > + return ret;
> > + }
>
> Not related to this patch, but what's the reason for waiting for the link to
> enter L2? There are a few other drivers that do this, but most don't. Is
> there something else the driver needs to do after the link is in L2?
>
Agree with you, I used to suggest Frank to remove the L2 polling too.
Best Regards
Richard Zhu
> > }
> >
> > if (pci->pp.ops->deinit)
> > --
> > 2.37.1
> >
