> -----Original Message-----
> From: Tim Harvey <tharvey@xxxxxxxxxxxxx>
> Sent: 2025年6月7日 5:04
> To: Hongxing Zhu <hongxing.zhu@xxxxxxx>
> Cc: l.stach@xxxxxxxxxxxxxx; bhelgaas@xxxxxxxxxx; lpieralisi@xxxxxxxxxx;
> kw@xxxxxxxxx; manivannan.sadhasivam@xxxxxxxxxx; robh@xxxxxxxxxx;
> krzk+dt@xxxxxxxxxx; conor+dt@xxxxxxxxxx; shawnguo@xxxxxxxxxx; Frank Li
> <frank.li@xxxxxxx>; s.hauer@xxxxxxxxxxxxxx; festevam@xxxxxxxxx;
> imx@xxxxxxxxxxxxxxx; kernel@xxxxxxxxxxxxxx; linux-pci@xxxxxxxxxxxxxxx;
> linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx;
> linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: [PATCH v7 05/10] PCI: imx6: Deassert apps_reset in
> imx_pcie_deassert_core_reset()
>
> On Tue, Nov 26, 2024 at 12:03 AM Richard Zhu <hongxing.zhu@xxxxxxx>
> wrote:
> >
> > Since the apps_reset is asserted in imx_pcie_assert_core_reset(), it
> > should be deasserted in imx_pcie_deassert_core_reset().
> >
> > Fixes: 9b3fe6796d7c ("PCI: imx6: Add code to support i.MX7D")
> > Signed-off-by: Richard Zhu <hongxing.zhu@xxxxxxx>
> > Reviewed-by: Manivannan Sadhasivam
> <manivannan.sadhasivam@xxxxxxxxxx>
> > Reviewed-by: Frank Li <Frank.Li@xxxxxxx>
> > ---
> > drivers/pci/controller/dwc/pci-imx6.c | 1 +
> > 1 file changed, 1 insertion(+)
> >
> > diff --git a/drivers/pci/controller/dwc/pci-imx6.c
> > b/drivers/pci/controller/dwc/pci-imx6.c
> > index 3538440601a7..413db182ce9f 100644
> > --- a/drivers/pci/controller/dwc/pci-imx6.c
> > +++ b/drivers/pci/controller/dwc/pci-imx6.c
> > @@ -776,6 +776,7 @@ static void imx_pcie_assert_core_reset(struct
> > imx_pcie *imx_pcie) static int imx_pcie_deassert_core_reset(struct
> > imx_pcie *imx_pcie) {
> > reset_control_deassert(imx_pcie->pciephy_reset);
> > + reset_control_deassert(imx_pcie->apps_reset);
> >
> > if (imx_pcie->drvdata->core_reset)
> > imx_pcie->drvdata->core_reset(imx_pcie, false);
> > --
> > 2.37.1
> >
> >
>
> Hi Richard,
>
> I've found that this patch causes a regression on i.MX8MM and i.MX8MP
> boards with hotplug capable bridges:
> i.MX8MM+PI7C9X2G404EV (this switch does not support hotplug) - no issues
> i.MX8MM+PI7C9X2G608GP (hotplug) - fails to reliably enumerate
> downstream devices about 80% of the time ^^^ when this occurs
> PCI_PRIMARY_BUS (0x18) for the root complex
> 0000:00:00.0 reads 0x00000000 instead of 0x00ff0100
> (PCI_SECONDARY_BUS is 0 instead of 1 and PCI_SUBBORDINATE_BUS is 0
> instead of 0xff) i.MX8MP+PI7C9X2G608GP (hotplug) - hangs at
> imx_pcie_ltssm_enable deassert apps_reset
>
> In both cases here reverting ef61c7d8d032 ("PCI: imx6: Deassert apps_reset
> in imx_pcie_deassert_core_reset()") resolves this.
>
[Richard Zhu] I'm afraid that the ltssm_en bit assert to 1b'1 in
imx_pcie_deassert_core_reset() is not correct in your use case.
Actually, the apps_reset isn't a real reset. It's the ltssm_en bit.
