[PATCH v3 1/4] phy: rockchip-emmc: Allow to set drive impedance via DTS.

[PATCH v3 1/4] phy: rockchip-emmc: Allow to set drive impedance via DTS.

[Christoph Muellner]

The rockchip-emmc PHY can be configured with different
drive impedance values. Currenlty a value of 50 Ohm is
hard coded into the driver.

This patch introduces the DTS property 'drive-impedance-ohm'
for the rockchip-emmc phy node, which uses the value from the DTS
to setup the drive impedance accordingly.

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
---
 drivers/phy/rockchip/phy-rockchip-emmc.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
index 19bf84f0bc67..b804c6bf4b55 100644
--- a/drivers/phy/rockchip/phy-rockchip-emmc.c
+++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
@@ -87,6 +87,7 @@ struct rockchip_emmc_phy {
 	unsigned int	reg_offset;
 	struct regmap	*reg_base;
 	struct clk	*emmcclk;
+	unsigned int drive_impedance;
 };
 
 static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
@@ -281,10 +282,10 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
 {
 	struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
 
-	/* Drive impedance: 50 Ohm */
+	/* Drive impedance: from DTS */
 	regmap_write(rk_phy->reg_base,
 		     rk_phy->reg_offset + GRF_EMMCPHY_CON6,
-		     HIWORD_UPDATE(PHYCTRL_DR_50OHM,
+		     HIWORD_UPDATE(rk_phy->drive_impedance,
 				   PHYCTRL_DR_MASK,
 				   PHYCTRL_DR_SHIFT));
 
@@ -314,6 +315,26 @@ static const struct phy_ops ops = {
 	.owner		= THIS_MODULE,
 };
 
+static u32 convert_drive_impedance_ohm(struct platform_device *pdev, u32 dr_ohm)
+{
+	switch (dr_ohm) {
+	case 100:
+		return PHYCTRL_DR_100OHM;
+	case 66:
+		return PHYCTRL_DR_66OHM;
+	case 50:
+		return PHYCTRL_DR_50OHM;
+	case 40:
+		return PHYCTRL_DR_40OHM;
+	case 33:
+		return PHYCTRL_DR_33OHM;
+	}
+
+	dev_warn(&pdev->dev, "Invalid value %u for drive-impedance-ohm.\n",
+		 dr_ohm);
+	return PHYCTRL_DR_50OHM;
+}
+
 static int rockchip_emmc_phy_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -322,6 +343,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
 	struct phy_provider *phy_provider;
 	struct regmap *grf;
 	unsigned int reg_offset;
+	u32 val;
 
 	if (!dev->parent || !dev->parent->of_node)
 		return -ENODEV;
@@ -344,6 +366,10 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
 
 	rk_phy->reg_offset = reg_offset;
 	rk_phy->reg_base = grf;
+	rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
+
+	if (!of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val))
+		rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
 
 	generic_phy = devm_phy_create(dev, dev->of_node, &ops);
 	if (IS_ERR(generic_phy)) {
-- 
2.11.0

[PATCH v3 1/4] phy: rockchip-emmc: Allow to set drive impedance via DTS.

[Christoph Muellner]

The rockchip-emmc PHY can be configured with different
drive impedance values. Currenlty a value of 50 Ohm is
hard coded into the driver.

This patch introduces the DTS property 'drive-impedance-ohm'
for the rockchip-emmc phy node, which uses the value from the DTS
to setup the drive impedance accordingly.

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
---
 drivers/phy/rockchip/phy-rockchip-emmc.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
index 19bf84f0bc67..b804c6bf4b55 100644
--- a/drivers/phy/rockchip/phy-rockchip-emmc.c
+++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
@@ -87,6 +87,7 @@ struct rockchip_emmc_phy {
 	unsigned int	reg_offset;
 	struct regmap	*reg_base;
 	struct clk	*emmcclk;
+	unsigned int drive_impedance;
 };
 
 static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
@@ -281,10 +282,10 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
 {
 	struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
 
-	/* Drive impedance: 50 Ohm */
+	/* Drive impedance: from DTS */
 	regmap_write(rk_phy->reg_base,
 		     rk_phy->reg_offset + GRF_EMMCPHY_CON6,
-		     HIWORD_UPDATE(PHYCTRL_DR_50OHM,
+		     HIWORD_UPDATE(rk_phy->drive_impedance,
 				   PHYCTRL_DR_MASK,
 				   PHYCTRL_DR_SHIFT));
 
@@ -314,6 +315,26 @@ static const struct phy_ops ops = {
 	.owner		= THIS_MODULE,
 };
 
+static u32 convert_drive_impedance_ohm(struct platform_device *pdev, u32 dr_ohm)
+{
+	switch (dr_ohm) {
+	case 100:
+		return PHYCTRL_DR_100OHM;
+	case 66:
+		return PHYCTRL_DR_66OHM;
+	case 50:
+		return PHYCTRL_DR_50OHM;
+	case 40:
+		return PHYCTRL_DR_40OHM;
+	case 33:
+		return PHYCTRL_DR_33OHM;
+	}
+
+	dev_warn(&pdev->dev, "Invalid value %u for drive-impedance-ohm.\n",
+		 dr_ohm);
+	return PHYCTRL_DR_50OHM;
+}
+
 static int rockchip_emmc_phy_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -322,6 +343,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
 	struct phy_provider *phy_provider;
 	struct regmap *grf;
 	unsigned int reg_offset;
+	u32 val;
 
 	if (!dev->parent || !dev->parent->of_node)
 		return -ENODEV;
@@ -344,6 +366,10 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
 
 	rk_phy->reg_offset = reg_offset;
 	rk_phy->reg_base = grf;
+	rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
+
+	if (!of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val))
+		rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
 
 	generic_phy = devm_phy_create(dev, dev->of_node, &ops);
 	if (IS_ERR(generic_phy)) {
-- 
2.11.0

[PATCH v3 1/4] phy: rockchip-emmc: Allow to set drive impedance via DTS.

[Christoph Muellner]

The rockchip-emmc PHY can be configured with different
drive impedance values. Currenlty a value of 50 Ohm is
hard coded into the driver.

This patch introduces the DTS property 'drive-impedance-ohm'
for the rockchip-emmc phy node, which uses the value from the DTS
to setup the drive impedance accordingly.

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
---
 drivers/phy/rockchip/phy-rockchip-emmc.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/drivers/phy/rockchip/phy-rockchip-emmc.c b/drivers/phy/rockchip/phy-rockchip-emmc.c
index 19bf84f0bc67..b804c6bf4b55 100644
--- a/drivers/phy/rockchip/phy-rockchip-emmc.c
+++ b/drivers/phy/rockchip/phy-rockchip-emmc.c
@@ -87,6 +87,7 @@ struct rockchip_emmc_phy {
 	unsigned int	reg_offset;
 	struct regmap	*reg_base;
 	struct clk	*emmcclk;
+	unsigned int drive_impedance;
 };
 
 static int rockchip_emmc_phy_power(struct phy *phy, bool on_off)
@@ -281,10 +282,10 @@ static int rockchip_emmc_phy_power_on(struct phy *phy)
 {
 	struct rockchip_emmc_phy *rk_phy = phy_get_drvdata(phy);
 
-	/* Drive impedance: 50 Ohm */
+	/* Drive impedance: from DTS */
 	regmap_write(rk_phy->reg_base,
 		     rk_phy->reg_offset + GRF_EMMCPHY_CON6,
-		     HIWORD_UPDATE(PHYCTRL_DR_50OHM,
+		     HIWORD_UPDATE(rk_phy->drive_impedance,
 				   PHYCTRL_DR_MASK,
 				   PHYCTRL_DR_SHIFT));
 
@@ -314,6 +315,26 @@ static const struct phy_ops ops = {
 	.owner		= THIS_MODULE,
 };
 
+static u32 convert_drive_impedance_ohm(struct platform_device *pdev, u32 dr_ohm)
+{
+	switch (dr_ohm) {
+	case 100:
+		return PHYCTRL_DR_100OHM;
+	case 66:
+		return PHYCTRL_DR_66OHM;
+	case 50:
+		return PHYCTRL_DR_50OHM;
+	case 40:
+		return PHYCTRL_DR_40OHM;
+	case 33:
+		return PHYCTRL_DR_33OHM;
+	}
+
+	dev_warn(&pdev->dev, "Invalid value %u for drive-impedance-ohm.\n",
+		 dr_ohm);
+	return PHYCTRL_DR_50OHM;
+}
+
 static int rockchip_emmc_phy_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -322,6 +343,7 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
 	struct phy_provider *phy_provider;
 	struct regmap *grf;
 	unsigned int reg_offset;
+	u32 val;
 
 	if (!dev->parent || !dev->parent->of_node)
 		return -ENODEV;
@@ -344,6 +366,10 @@ static int rockchip_emmc_phy_probe(struct platform_device *pdev)
 
 	rk_phy->reg_offset = reg_offset;
 	rk_phy->reg_base = grf;
+	rk_phy->drive_impedance = PHYCTRL_DR_50OHM;
+
+	if (!of_property_read_u32(dev->of_node, "drive-impedance-ohm", &val))
+		rk_phy->drive_impedance = convert_drive_impedance_ohm(pdev, val);
 
 	generic_phy = devm_phy_create(dev, dev->of_node, &ops);
 	if (IS_ERR(generic_phy)) {
-- 
2.11.0


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[PATCH v3 2/4] dt-bindings: phy: Add a new property drive-impedance-ohm for RK's emmc PHY

[Christoph Muellner]

This patch documents the new proprty drive-impedance-ohm for
Rockchip's eMMC PHY node.

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
---
 Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt b/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
index e3ea55763b0a..e728786f21e0 100644
--- a/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
+++ b/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
@@ -7,12 +7,15 @@ Required properties:
  - reg: PHY register address offset and length in "general
    register files"
 
-Optional clocks using the clock bindings (see ../clock/clock-bindings.txt),
-specified by name:
+Optional properties:
  - clock-names: Should contain "emmcclk".  Although this is listed as optional
 		(because most boards can get basic functionality without having
 		access to it), it is strongly suggested.
+		See ../clock/clock-bindings.txt for details.
  - clocks: Should have a phandle to the card clock exported by the SDHCI driver.
+ - drive-impedance-ohm: Specifies the drive impedance in Ohm.
+                        Possible values are 33, 40, 50, 66 and 100.
+                        If not set, the default value of 50 will be applied.
 
 Example:
 
@@ -29,6 +32,7 @@ grf: syscon@ff770000 {
 		reg = <0xf780 0x20>;
 		clocks = <&sdhci>;
 		clock-names = "emmcclk";
+		drive-impedance-ohm = <50>;
 		#phy-cells = <0>;
 	};
 };
-- 
2.11.0

[PATCH v3 2/4] dt-bindings: phy: Add a new property drive-impedance-ohm for RK's emmc PHY

[Christoph Muellner]

This patch documents the new proprty drive-impedance-ohm for
Rockchip's eMMC PHY node.

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
---
 Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt b/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
index e3ea55763b0a..e728786f21e0 100644
--- a/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
+++ b/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
@@ -7,12 +7,15 @@ Required properties:
  - reg: PHY register address offset and length in "general
    register files"
 
-Optional clocks using the clock bindings (see ../clock/clock-bindings.txt),
-specified by name:
+Optional properties:
  - clock-names: Should contain "emmcclk".  Although this is listed as optional
 		(because most boards can get basic functionality without having
 		access to it), it is strongly suggested.
+		See ../clock/clock-bindings.txt for details.
  - clocks: Should have a phandle to the card clock exported by the SDHCI driver.
+ - drive-impedance-ohm: Specifies the drive impedance in Ohm.
+                        Possible values are 33, 40, 50, 66 and 100.
+                        If not set, the default value of 50 will be applied.
 
 Example:
 
@@ -29,6 +32,7 @@ grf: syscon@ff770000 {
 		reg = <0xf780 0x20>;
 		clocks = <&sdhci>;
 		clock-names = "emmcclk";
+		drive-impedance-ohm = <50>;
 		#phy-cells = <0>;
 	};
 };
-- 
2.11.0

[PATCH v3 2/4] dt-bindings: phy: Add a new property drive-impedance-ohm for RK's emmc PHY

[Christoph Muellner]

This patch documents the new proprty drive-impedance-ohm for
Rockchip's eMMC PHY node.

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
---
 Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt b/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
index e3ea55763b0a..e728786f21e0 100644
--- a/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
+++ b/Documentation/devicetree/bindings/phy/rockchip-emmc-phy.txt
@@ -7,12 +7,15 @@ Required properties:
  - reg: PHY register address offset and length in "general
    register files"
 
-Optional clocks using the clock bindings (see ../clock/clock-bindings.txt),
-specified by name:
+Optional properties:
  - clock-names: Should contain "emmcclk".  Although this is listed as optional
 		(because most boards can get basic functionality without having
 		access to it), it is strongly suggested.
+		See ../clock/clock-bindings.txt for details.
  - clocks: Should have a phandle to the card clock exported by the SDHCI driver.
+ - drive-impedance-ohm: Specifies the drive impedance in Ohm.
+                        Possible values are 33, 40, 50, 66 and 100.
+                        If not set, the default value of 50 will be applied.
 
 Example:
 
@@ -29,6 +32,7 @@ grf: syscon@ff770000 {
 		reg = <0xf780 0x20>;
 		clocks = <&sdhci>;
 		clock-names = "emmcclk";
+		drive-impedance-ohm = <50>;
 		#phy-cells = <0>;
 	};
 };
-- 
2.11.0


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[PATCH v3 3/4] arm64: dts: rockchip: Define drive-impedance-ohm for RK3399's emmc-phy.

[Christoph Muellner]

A previous patch introduced the property 'drive-impedance-ohm'
for the RK3399's emmc phy node. This patch sets this value
explicitly to the default value of 50 Ohm.

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
---
 arch/arm64/boot/dts/rockchip/rk3399.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
index db9d948c0b03..1f1f7732ae76 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
@@ -1450,6 +1450,7 @@
 			clock-names = "refclk";
 			#phy-cells = <1>;
 			resets = <&cru SRST_PCIEPHY>;
+			drive-impedance-ohm = <50>;
 			reset-names = "phy";
 			status = "disabled";
 		};
-- 
2.11.0

[PATCH v3 3/4] arm64: dts: rockchip: Define drive-impedance-ohm for RK3399's emmc-phy.

[Christoph Muellner]

A previous patch introduced the property 'drive-impedance-ohm'
for the RK3399's emmc phy node. This patch sets this value
explicitly to the default value of 50 Ohm.

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
---
 arch/arm64/boot/dts/rockchip/rk3399.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
index db9d948c0b03..1f1f7732ae76 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
@@ -1450,6 +1450,7 @@
 			clock-names = "refclk";
 			#phy-cells = <1>;
 			resets = <&cru SRST_PCIEPHY>;
+			drive-impedance-ohm = <50>;
 			reset-names = "phy";
 			status = "disabled";
 		};
-- 
2.11.0

[PATCH v3 3/4] arm64: dts: rockchip: Define drive-impedance-ohm for RK3399's emmc-phy.

[Christoph Muellner]

A previous patch introduced the property 'drive-impedance-ohm'
for the RK3399's emmc phy node. This patch sets this value
explicitly to the default value of 50 Ohm.

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
---
 arch/arm64/boot/dts/rockchip/rk3399.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399.dtsi b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
index db9d948c0b03..1f1f7732ae76 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399.dtsi
@@ -1450,6 +1450,7 @@
 			clock-names = "refclk";
 			#phy-cells = <1>;
 			resets = <&cru SRST_PCIEPHY>;
+			drive-impedance-ohm = <50>;
 			reset-names = "phy";
 			status = "disabled";
 		};
-- 
2.11.0


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[PATCH v3 4/4] arm64: dts: rockchip: Decrease emmc-phy's drive impedance on rk3399-puma

[Christoph Muellner]

The RK3399-Q7 (Puma) requires 33 Ohm drive strength to ensure signal
integrity at HS-400 (200MHz clock, DDR signalling).

A repeated EMC testing run validates that this increase does not
negatively impact EMC compliance (emissions have ample distance to
the regulatory limits).

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: Jakob Unterwurzacher <jakob.unterwurzacher@theobroma-systems.com>
Tested-by: Klaus Goger <klaus.goger@theobroma-systems.com>
---
 arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
index 0130b9f98c9d..4f75bb6b2f14 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
@@ -146,6 +146,7 @@
 
 &emmc_phy {
 	status = "okay";
+	drive-impedance-ohm = <33>;
 };
 
 &gmac {
-- 
2.11.0

[PATCH v3 4/4] arm64: dts: rockchip: Decrease emmc-phy's drive impedance on rk3399-puma

[Christoph Muellner]

The RK3399-Q7 (Puma) requires 33 Ohm drive strength to ensure signal
integrity at HS-400 (200MHz clock, DDR signalling).

A repeated EMC testing run validates that this increase does not
negatively impact EMC compliance (emissions have ample distance to
the regulatory limits).

Signed-off-by: Christoph Muellner <christoph.muellner-SN7IsUiht6C/RdPyistoZJqQE7yCjDx5@public.gmane.org>
Signed-off-by: Philipp Tomsich <philipp.tomsich-SN7IsUiht6C/RdPyistoZJqQE7yCjDx5@public.gmane.org>
Tested-by: Jakob Unterwurzacher <jakob.unterwurzacher-SN7IsUiht6C/RdPyistoZJqQE7yCjDx5@public.gmane.org>
Tested-by: Klaus Goger <klaus.goger-SN7IsUiht6C/RdPyistoZJqQE7yCjDx5@public.gmane.org>
---
 arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
index 0130b9f98c9d..4f75bb6b2f14 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
@@ -146,6 +146,7 @@
 
 &emmc_phy {
 	status = "okay";
+	drive-impedance-ohm = <33>;
 };
 
 &gmac {
-- 
2.11.0

[PATCH v3 4/4] arm64: dts: rockchip: Decrease emmc-phy's drive impedance on rk3399-puma

[Christoph Muellner]

The RK3399-Q7 (Puma) requires 33 Ohm drive strength to ensure signal
integrity at HS-400 (200MHz clock, DDR signalling).

A repeated EMC testing run validates that this increase does not
negatively impact EMC compliance (emissions have ample distance to
the regulatory limits).

Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Tested-by: Jakob Unterwurzacher <jakob.unterwurzacher@theobroma-systems.com>
Tested-by: Klaus Goger <klaus.goger@theobroma-systems.com>
---
 arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi | 1 +
 1 file changed, 1 insertion(+)

diff --git a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
index 0130b9f98c9d..4f75bb6b2f14 100644
--- a/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
+++ b/arch/arm64/boot/dts/rockchip/rk3399-puma.dtsi
@@ -146,6 +146,7 @@
 
 &emmc_phy {
 	status = "okay";
+	drive-impedance-ohm = <33>;
 };
 
 &gmac {
-- 
2.11.0


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Re: [PATCH v3 3/4] arm64: dts: rockchip: Define drive-impedance-ohm for RK3399's emmc-phy.

[Heiko Stuebner]

Am Freitag, 22. März 2019, 12:34:52 CET schrieb Christoph Muellner:
> A previous patch introduced the property 'drive-impedance-ohm'
> for the RK3399's emmc phy node. This patch sets this value
> explicitly to the default value of 50 Ohm.
> 
> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
> Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

applied patches 3+4 for 5.2

Thanks
Heiko

Re: [PATCH v3 3/4] arm64: dts: rockchip: Define drive-impedance-ohm for RK3399's emmc-phy.

[Heiko Stuebner]

Am Freitag, 22. März 2019, 12:34:52 CET schrieb Christoph Muellner:
> A previous patch introduced the property 'drive-impedance-ohm'
> for the RK3399's emmc phy node. This patch sets this value
> explicitly to the default value of 50 Ohm.
> 
> Signed-off-by: Christoph Muellner <christoph.muellner@theobroma-systems.com>
> Signed-off-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>

applied patches 3+4 for 5.2

Thanks
Heiko



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