linux-kernel - [PATCH] PCI: imx6: Override the CLKREQ low in the initialization

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Date:   Wed, 23 Feb 2022 16:38:33 +0800
From:   Richard Zhu <hongxing.zhu@....com>
To:     l.stach@...gutronix.de, bhelgaas@...gle.com,
        lorenzo.pieralisi@....com
Cc:     linux-pci@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, kernel@...gutronix.de,
        linux-imx@....com, Richard Zhu <hongxing.zhu@....com>
Subject: [PATCH] PCI: imx6: Override the CLKREQ low in the initialization

The CLKREQ# signal is an open drain, active low signal that is driven
low by the remote Endpoint device. But it might not be driven low if no
Endpoint device is connected.

On i.MX8MM PCIe, phy_init() would be failed and system boot hang if the
reference clock is not toggled.

Follow with i.MX8MQ PCIe, to make sure the reference clock on, override
the CLKREQ# low during initialization to fix this issue.

Fixes: 178e244cb6e2 ("PCI: imx: Add the imx8mm pcie support")
Signed-off-by: Richard Zhu <hongxing.zhu@....com>
---
 drivers/pci/controller/dwc/pci-imx6.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index d7f0db01f3c3..a334341a1789 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -447,10 +447,6 @@ static int imx6_pcie_enable_ref_clk(struct imx6_pcie *imx6_pcie)
 	case IMX7D:
 		break;
 	case IMX8MM:
-		ret = clk_prepare_enable(imx6_pcie->pcie_aux);
-		if (ret)
-			dev_err(dev, "unable to enable pcie_aux clock\n");
-		break;
 	case IMX8MQ:
 		ret = clk_prepare_enable(imx6_pcie->pcie_aux);
 		if (ret) {
-- 
2.25.1