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From:   Christian Marangi <ansuelsmth@gmail.com>
To:     Stanimir Varbanov <svarbanov@mm-sol.com>,
        Andy Gross <agross@kernel.org>,
        Bjorn Andersson <bjorn.andersson@linaro.org>,
        Konrad Dybcio <konrad.dybcio@somainline.org>,
        Lorenzo Pieralisi <lpieralisi@kernel.org>,
        Rob Herring <robh@kernel.org>,
        =?UTF-8?q?Krzysztof=20Wilczy=C5=84ski?= <kw@linux.com>,
        Bjorn Helgaas <bhelgaas@google.com>, linux-pci@vger.kernel.org,
        linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     Christian Marangi <ansuelsmth@gmail.com>, stable@vger.kernel.org
Subject: [PATCH] PCI: qcom: Enable clocks only after PARF_PHY setup for rev 2.1.0
Date:   Sat,  9 Jul 2022 00:27:43 +0200
Message-Id: <20220708222743.27019-1-ansuelsmth@gmail.com>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

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

This in fact 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 setup the pcie line and makes it usable even when a
bootloader leave the pcie line to a underfined state.

Fixes: 82a823833f4e ("PCI: qcom: Add Qualcomm PCIe controller driver")
Cc: stable@vger.kernel.org # v5.4+
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
---
 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 2ea13750b492..da13a66ced14 100644
--- a/drivers/pci/controller/dwc/pcie-qcom.c
+++ b/drivers/pci/controller/dwc/pcie-qcom.c
@@ -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) |
-- 
2.36.1