[RESEND PATCH v1 0/2] PCI: imx6: Add external reference clock mode

[RESEND PATCH v1 0/2] PCI: imx6: Add external reference clock mode

[Richard Zhu]

On i.MX, the PCIe reference clock might come from either internal
system PLL or external clock source.
Add the external reference clock source for reference clock.

It's my fault missing add the necessary people and lists of dt-binding
review. Resend the v1 patch-set after correct dt-binding review pepople
and list. All the comments would be addressed, then send out v2 later.

[RESEND PATCH v1 1/2] dt-binding: pci-imx6: Add external reference
[RESEND PATCH v1 2/2] PCI: imx6: Add external reference clock mode

Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml |  7 ++++++-
drivers/pci/controller/dwc/pci-imx6.c                     | 34 ++++++++++++++++++++++++++--------
2 files changed, 32 insertions(+), 9 deletions(-)

[RESEND PATCH v1 1/2] dt-binding: pci-imx6: Add external reference clock mode support

[Richard Zhu]

On i.MX, the PCIe reference clock might come from either internal
system PLL or external clock source.
Add the external reference clock source for reference clock.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
---
 Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml
index ca5f2970f217..4b99fa8e7a25 100644
--- a/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml
+++ b/Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml
@@ -219,7 +219,12 @@ allOf:
             - const: pcie_bus
             - const: pcie_phy
             - const: pcie_aux
-            - const: ref
+            - description: PCIe reference clock.
+              oneOf:
+              - description: The controller might be configured clocking
+                  coming in from either an internal system PLL or an
+                  external clock source.
+              enum: [ref, gio]
 
 unevaluatedProperties: false
 
-- 
2.37.1

[RESEND PATCH v1 2/2] PCI: imx6: Add external reference clock mode support

[Richard Zhu]

The PCI Express reference clock of i.MX9 PCIes might come from external
clock source. Add the external reference clock mode support.

Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
---
 drivers/pci/controller/dwc/pci-imx6.c | 34 ++++++++++++++++++++-------
 1 file changed, 26 insertions(+), 8 deletions(-)

diff --git a/drivers/pci/controller/dwc/pci-imx6.c b/drivers/pci/controller/dwc/pci-imx6.c
index 5a38cfaf989b..04c720377546 100644
--- a/drivers/pci/controller/dwc/pci-imx6.c
+++ b/drivers/pci/controller/dwc/pci-imx6.c
@@ -149,6 +149,7 @@ struct imx_pcie {
 	struct gpio_desc	*reset_gpiod;
 	struct clk_bulk_data	*clks;
 	int			num_clks;
+	bool			enable_ext_refclk;
 	struct regmap		*iomuxc_gpr;
 	u16			msi_ctrl;
 	u32			controller_id;
@@ -259,13 +260,24 @@ static int imx95_pcie_init_phy(struct imx_pcie *imx_pcie)
 			IMX95_PCIE_PHY_CR_PARA_SEL,
 			IMX95_PCIE_PHY_CR_PARA_SEL);
 
-	regmap_update_bits(imx_pcie->iomuxc_gpr,
-			   IMX95_PCIE_PHY_GEN_CTRL,
-			   IMX95_PCIE_REF_USE_PAD, 0);
-	regmap_update_bits(imx_pcie->iomuxc_gpr,
-			   IMX95_PCIE_SS_RW_REG_0,
-			   IMX95_PCIE_REF_CLKEN,
-			   IMX95_PCIE_REF_CLKEN);
+	if (imx_pcie->enable_ext_refclk) {
+		/* External clock is used as reference clock */
+		regmap_update_bits(imx_pcie->iomuxc_gpr,
+				   IMX95_PCIE_PHY_GEN_CTRL,
+				   IMX95_PCIE_REF_USE_PAD,
+				   IMX95_PCIE_REF_USE_PAD);
+		regmap_update_bits(imx_pcie->iomuxc_gpr,
+				   IMX95_PCIE_SS_RW_REG_0,
+				   IMX95_PCIE_REF_CLKEN, 0);
+	} else {
+		regmap_update_bits(imx_pcie->iomuxc_gpr,
+				   IMX95_PCIE_PHY_GEN_CTRL,
+				   IMX95_PCIE_REF_USE_PAD, 0);
+		regmap_update_bits(imx_pcie->iomuxc_gpr,
+				   IMX95_PCIE_SS_RW_REG_0,
+				   IMX95_PCIE_REF_CLKEN,
+				   IMX95_PCIE_REF_CLKEN);
+	}
 
 	return 0;
 }
@@ -1600,7 +1612,7 @@ static int imx_pcie_probe(struct platform_device *pdev)
 	struct imx_pcie *imx_pcie;
 	struct device_node *np;
 	struct device_node *node = dev->of_node;
-	int ret, domain;
+	int i, ret, domain;
 	u16 val;
 
 	imx_pcie = devm_kzalloc(dev, sizeof(*imx_pcie), GFP_KERNEL);
@@ -1651,6 +1663,12 @@ static int imx_pcie_probe(struct platform_device *pdev)
 	if (imx_pcie->num_clks < 0)
 		return dev_err_probe(dev, imx_pcie->num_clks,
 				     "failed to get clocks\n");
+	for (i = 0; i < imx_pcie->num_clks; i++) {
+		if (strncmp(imx_pcie->clks[i].id, "ref", 3) == 0)
+			imx_pcie->enable_ext_refclk = false;
+		else
+			imx_pcie->enable_ext_refclk = true;
+	}
 
 	if (imx_check_flag(imx_pcie, IMX_PCIE_FLAG_HAS_PHYDRV)) {
 		imx_pcie->phy = devm_phy_get(dev, "pcie-phy");
-- 
2.37.1

Re: [RESEND PATCH v1 1/2] dt-binding: pci-imx6: Add external reference clock mode support

[Rob Herring (Arm)]

On Thu, 19 Jun 2025 13:55:14 +0800, Richard Zhu wrote:
> On i.MX, the PCIe reference clock might come from either internal
> system PLL or external clock source.
> Add the external reference clock source for reference clock.
> 
> Signed-off-by: Richard Zhu <hongxing.zhu@nxp.com>
> ---
>  Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 

My bot found errors running 'make dt_binding_check' on your patch:

yamllint warnings/errors:
./Documentation/devicetree/bindings/pci/fsl,imx6q-pcie.yaml:224:15: [warning] wrong indentation: expected 16 but found 14 (indentation)

dtschema/dtc warnings/errors:

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/project/devicetree-bindings/patch/20250619055515.74675-2-hongxing.zhu@nxp.com

The base for the series is generally the latest rc1. A different dependency
should be noted in *this* patch.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit after running the above command yourself. Note
that DT_SCHEMA_FILES can be set to your schema file to speed up checking
your schema. However, it must be unset to test all examples with your schema.