linux-kernel - [PATCH 5.10 320/545] PCI: qcom: Set up rev 2.1.0 PARF

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Date:   Fri, 19 Aug 2022 17:41:30 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Christian Marangi <ansuelsmth@...il.com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 5.10 320/545] PCI: qcom: Set up rev 2.1.0 PARF_PHY before enabling clocks

From: Christian Marangi <ansuelsmth@...il.com>

[ 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@...il.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/pci/controller/dwc/pcie-qcom.c | 10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-qcom.c b/drivers/pci/controller/dwc/pcie-qcom.c
index 1b8b3c12eece..5fbd80908a99 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -320,8 +320,6 @@ 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");
@@ -364,15 +362,15 @@ 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) |
-- 
2.35.1