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

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: 82a823833f ("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>
This commit is contained in:
Christian Marangi 2022-07-09 00:27:43 +02:00 committed by Bjorn Helgaas
parent 553d12b20c
commit 38f897ae3d
1 changed files with 4 additions and 6 deletions
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10
drivers/pci/controller/dwc/pcie-qcom.c
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@ -337,8 +337,6 @@ 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");
@ -381,15 +379,15 @@ 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) |