PCI: imx6: Remove apps_reset toggling from imx_pcie_{assert/deassert}_core_reset

apps_reset corresponds to LTSSM_EN in i.MX7, i.MX8MQ, i.MX8MM and i.MX8MP
platforms. Since assertion/de-assertion of apps_reset is done in
imx_pcie_ltssm_enable() and imx_pcie_ltssm_disable(), remove it from
imx_pcie_assert_core_reset() and imx_pcie_deassert_core_reset().

This also fixes a failure in enumerating the PI7C9X2G608GP (hotplug) chip
reliably on i.MX8MM, as reported by Tim.

It should be noted that only i.MX7D, i.MX8MQ, i.MX8MM, and i.MX8MP
platforms have the apps_reset logic, so this change doesn't have any effect
on other platforms.

Fixes: ef61c7d ("PCI: imx6: Deassert apps_reset in imx_pcie_deassert_core_reset()")
Reported-by: Tim Harvey <tharvey@gateworks.com>
Closes: https://lore.kernel.org/all/CAJ+vNU3ohR2YKTwC4xoYrc1z-neDoH2TTZcMHDy+poj9=jSy+w@mail.gmail.com/
Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
[mani: reworded commit subject and description]
Signed-off-by: Manivannan Sadhasivam <mani@kernel.org>
[bhelgaas: commit log]
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Tim Harvey <tharvey@gateworks.com> # imx8mp-venice-gw74xx (i.MX8MP + hotplug capable switch)
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20250709033722.2924372-2-hongxing.zhu@nxp.com

Author: Richard Zhu

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);
@@ -1253,6 +1251,9 @@ 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);