PCI: qcom: Make sure PCIe is reset before init for rev 2.1.0

Qsdk U-Boot can incorrectly leave the PCIe interface in an undefined
state if bootm command is used instead of bootipq. This is caused by the
not deinit of PCIe when bootm is called. Reset the PCIe before init
anyway to fix this U-Boot bug.

Link: https://lore.kernel.org/r/20200901124955.137-1-ansuelsmth@gmail.com
Fixes: 82a82383 ("PCI: qcom: Add Qualcomm PCIe controller driver")
Signed-off-by: Ansuel Smith <ansuelsmth@gmail.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Cc: stable@vger.kernel.org # v4.19+

drivers/pci/controller/dwc/pcie-qcom.c

@@ -302,6 +302,9 @@ static void qcom_pcie_deinit_2_1_0(struct qcom_pcie *pcie)
 	reset_control_assert(res->por_reset);
 	reset_control_assert(res->ext_reset);
 	reset_control_assert(res->phy_reset);
+
+	writel(1, pcie->parf + PCIE20_PARF_PHY_CTRL);
+
 	regulator_bulk_disable(ARRAY_SIZE(res->supplies), res->supplies);
 }
 
@@ -314,6 +317,16 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
 	u32 val;
 	int ret;
 
+	/* reset the PCIe interface as uboot can leave it undefined state */
+	reset_control_assert(res->pci_reset);
+	reset_control_assert(res->axi_reset);
+	reset_control_assert(res->ahb_reset);
+	reset_control_assert(res->por_reset);
+	reset_control_assert(res->ext_reset);
+	reset_control_assert(res->phy_reset);
+
+	writel(1, pcie->parf + PCIE20_PARF_PHY_CTRL);
+
 	ret = regulator_bulk_enable(ARRAY_SIZE(res->supplies), res->supplies);
 	if (ret < 0) {
 		dev_err(dev, "cannot enable regulators\n");