PCI: qcom: Set up rev 2.1.0 PARF_PHY before enabling clocks

[ Upstream commit 38f897ae3d44900f627cad708a15db498ce2ca31 ]

We currently enable clocks BEFORE we write to PARF_PHY_CTRL reg to enable
clocks and resets. This causes the driver to never set to a ready state
with the error 'Phy link never came up'.

This is caused by the PHY clock getting enabled before setting the required
bits in the PARF regs.

A workaround for this was set but with this new discovery we can drop
the workaround and use a proper solution to the problem by just enabling
the clock only AFTER the PARF_PHY_CTRL bit is set.

This correctly sets up the PCIe link and makes it usable even when a
bootloader leaves the PCIe link in an undefined state.

Fixes: 82a823833f4e ("PCI: qcom: Add Qualcomm PCIe controller driver")
Link: https://lore.kernel.org/r/20220708222743.27019-1-ansuelsmth@gmail.com
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index b139a2e..45210c6 100644 (file)
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -325,8 +325,6 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
        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");
@@ -369,15 +367,15 @@ static int qcom_pcie_init_2_1_0(struct qcom_pcie *pcie)
                goto err_deassert_axi;
        }
 
-       ret = clk_bulk_prepare_enable(ARRAY_SIZE(res->clks), res->clks);
-       if (ret)
-               goto err_clks;
-
        /* enable PCIe clocks and resets */
        val = readl(pcie->parf + PCIE20_PARF_PHY_CTRL);
        val &= ~BIT(0);
        writel(val, pcie->parf + PCIE20_PARF_PHY_CTRL);
 
+       ret = clk_bulk_prepare_enable(ARRAY_SIZE(res->clks), res->clks);
+       if (ret)
+               goto err_clks;
+
        if (of_device_is_compatible(node, "qcom,pcie-ipq8064") ||
            of_device_is_compatible(node, "qcom,pcie-ipq8064-v2")) {
                writel(PCS_DEEMPH_TX_DEEMPH_GEN1(24) |