[PATCH v3 1/2] PCI: imx6: Remove apps_reset toggle in _core_reset functions

[Tim Harvey]

On Mon, Jun 16, 2025 at 1:59 AM Richard Zhu <hongxing.zhu at nxp.com> wrote:
>
> apps_reset is LTSSM_EN on i.MX7, i.MX8MQ, i.MX8MM and i.MX8MP platforms.
> Since the assertion/de-assertion of apps_reset(LTSSM_EN bit) had been
> wrappered in imx_pcie_ltssm_enable() and imx_pcie_ltssm_disable();
>
> Remove apps_reset toggle in imx_pcie_assert_core_reset() and
> imx_pcie_deassert_core_reset() functions. Use imx_pcie_ltssm_enable()
> and imx_pcie_ltssm_disable() to configure apps_reset directly.
>
> Fix fail to enumerate reliably PI7C9X2G608GP (hotplug) at i.MX8MM, which
> reported By Tim.
>
> Reported-by: Tim Harvey <tharvey at gateworks.com>
> Closes: https://lore.kernel.org/all/CAJ+vNU3ohR2YKTwC4xoYrc1z-neDoH2TTZcMHDy+poj9=jSy+w@mail.gmail.com/
> Fixes: ef61c7d8d032 ("PCI: imx6: Deassert apps_reset in imx_pcie_deassert_core_reset()")
> Signed-off-by: Richard Zhu <hongxing.zhu at nxp.com>
> Reviewed-by: Frank Li <Frank.Li at nxp.com>
> ---
>  drivers/pci/controller/dwc/pci-imx6.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
> index 9754cc6e09b9..f5f2ac638f4b 100644
> --- a/drivers/pci/controller/dwc/pci-imx6.c
> +++ b/drivers/pci/controller/dwc/pci-imx6.c
> @@ -860,7 +860,6 @@ static int imx95_pcie_core_reset(struct imx_pcie *imx_pcie, bool assert)
>  static void imx_pcie_assert_core_reset(struct imx_pcie *imx_pcie)
>  {
>         reset_control_assert(imx_pcie->pciephy_reset);
> -       reset_control_assert(imx_pcie->apps_reset);
>
>         if (imx_pcie->drvdata->core_reset)
>                 imx_pcie->drvdata->core_reset(imx_pcie, true);
> @@ -872,7 +871,6 @@ 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);
> @@ -1247,6 +1245,9 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
>                 }
>         }
>
> +       /* Make sure that PCIe LTSSM is cleared */
> +       imx_pcie_ltssm_disable(dev);
> +
>         ret = imx_pcie_deassert_core_reset(imx_pcie);
>         if (ret < 0) {
>                 dev_err(dev, "pcie deassert core reset failed: %d\n", ret);
> --
> 2.37.1
>

Tested-by: Tim Harvey <tharvey at gateworks.com> # imx8mp-venice-gw74xx
(i.MX8MP + hotplug capable switch)

Best Regards,

Tim