[PATCH] PCI: imx6: Separate PERST# assertion from core reset functions

[Sherry Sun]

The imx_pcie_assert_core_reset() and imx_pcie_deassert_core_reset()
functions are primarily intended to reset the RC controller itself, not
the remote PCIe endpoint devices. However, the PERST# GPIO control was
previously embedded within these functions, which conflates two distinct
reset operations.

Move the PERST# GPIO handling into a dedicated function
imx_pcie_assert_perst(). This makes the code more maintainable and
prepares for parsing the reset-gpios property according to the new
Root Port DT binding in subsequent patches.

No functional change is intended.

Signed-off-by: Sherry Sun <sherry.sun@xxxxxxx>
---
 drivers/pci/controller/dwc/pci-imx6.c | 29 +++++++++++++++++----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index ba6e7c7ee625..d80d3be28ee5 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -901,9 +901,6 @@ static void imx_pcie_assert_core_reset(struct imx_pcie *imx_pcie)
 
 	if (imx_pcie->drvdata->core_reset)
 		imx_pcie->drvdata->core_reset(imx_pcie, true);
-
-	/* Some boards don't have PCIe reset GPIO. */
-	gpiod_set_value_cansleep(imx_pcie->reset_gpiod, 1);
 }
 
 static void imx_pcie_deassert_core_reset(struct imx_pcie *imx_pcie)
@@ -912,14 +909,6 @@ static void imx_pcie_deassert_core_reset(struct imx_pcie *imx_pcie)
 
 	if (imx_pcie->drvdata->core_reset)
 		imx_pcie->drvdata->core_reset(imx_pcie, false);
-
-	/* Some boards don't have PCIe reset GPIO. */
-	if (imx_pcie->reset_gpiod) {
-		msleep(100);
-		gpiod_set_value_cansleep(imx_pcie->reset_gpiod, 0);
-		/* Wait for 100ms after PERST# deassertion (PCIe r5.0, 6.6.1) */
-		msleep(100);
-	}
 }
 
 static int imx_pcie_wait_for_speed_change(struct imx_pcie *imx_pcie)
@@ -1231,6 +1220,19 @@ static void imx_pcie_disable_device(struct pci_host_bridge *bridge,
 	imx_pcie_remove_lut(imx_pcie, pci_dev_id(pdev));
 }
 
+static void imx_pcie_assert_perst(struct imx_pcie *imx_pcie, bool assert)
+{
+	if (assert) {
+		gpiod_set_value_cansleep(imx_pcie->reset_gpiod, 1);
+	} else {
+		if (imx_pcie->reset_gpiod) {
+			msleep(PCIE_T_PVPERL_MS);
+			gpiod_set_value_cansleep(imx_pcie->reset_gpiod, 0);
+			msleep(PCIE_RESET_CONFIG_WAIT_MS);
+		}
+	}
+}
+
 static int imx_pcie_host_init(struct dw_pcie_rp *pp)
 {
 	struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
@@ -1253,6 +1255,7 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
 	}
 
 	imx_pcie_assert_core_reset(imx_pcie);
+	imx_pcie_assert_perst(imx_pcie, true);
 
 	if (imx_pcie->drvdata->init_phy)
 		imx_pcie->drvdata->init_phy(imx_pcie);
@@ -1291,6 +1294,7 @@ static int imx_pcie_host_init(struct dw_pcie_rp *pp)
 	imx_pcie_ltssm_disable(dev);
 
 	imx_pcie_deassert_core_reset(imx_pcie);
+	imx_pcie_assert_perst(imx_pcie, false);
 
 	if (imx_pcie->drvdata->wait_pll_lock) {
 		ret = imx_pcie->drvdata->wait_pll_lock(imx_pcie);
@@ -1587,6 +1591,7 @@ static int imx_pcie_suspend_noirq(struct device *dev)
 		 * clock which saves some power.
 		 */
 		imx_pcie_assert_core_reset(imx_pcie);
+		imx_pcie_assert_perst(imx_pcie, true);
 		imx_pcie->drvdata->enable_ref_clk(imx_pcie, false);
 	} else {
 		return dw_pcie_suspend_noirq(imx_pcie->pci);
@@ -1608,6 +1613,7 @@ static int imx_pcie_resume_noirq(struct device *dev)
 		if (ret)
 			return ret;
 		imx_pcie_deassert_core_reset(imx_pcie);
+		imx_pcie_assert_perst(imx_pcie, false);
 
 		/*
 		 * Using PCIE_TEST_PD seems to disable MSI and powers down the
@@ -1845,6 +1851,7 @@ static void imx_pcie_shutdown(struct platform_device *pdev)
 
 	/* bring down link, so bootloader gets clean state in case of reboot */
 	imx_pcie_assert_core_reset(imx_pcie);
+	imx_pcie_assert_perst(imx_pcie, true);
 }
 
 static const struct imx_pcie_drvdata drvdata[] = {
-- 
2.37.1