ARM64: dts: meson-gxbb-odroidc2: switch ethernet phy mode to rgmii-txid

PATCH New Heiner Kallweit 2 participants 3 messages Feb 9, 2017 – Mar 2, 2017

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Device tree bindings Arm/Amlogic Meson SoC support

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Heiner Kallweit

author

2017-02-09 23:09 UTC #0 lore raw

PATCH 1/1 ARM64: dts: meson-gxbb-odroidc2: switch ethernet phy mode to rgmii-txid

Documentation/networking/phy.txt states:
Whenever possible,use the PHY side RGMII delay.

The board uses a RTl8211F phy which supports creating the needed tx delay internally. Therefore switch to rgmii-txid mode.

Signed-off-by Heiner Kallweit <[email protected]>

---
 arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts | 1 +
 1 file changed, 1 insertion(+)

arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts +1 -0

index 3877dda6..94896139 100644
@@ -152,6 +152,7 @@
 	pinctrl-0 = <&eth_rgmii_pins>;
 	pinctrl-names = "default";
 	phy-handle = <&eth_phy0>;
+	phy-mode = "rgmii-txid";
 
 	mdio {
 		compatible = "snps,dwmac-mdio";

Signature · 1 line

2.11.0

Jerome Brunet

reviewer

2017-03-02 10:22 UTC #1 lore raw

PATCH 1/1 ARM64: dts: meson-gxbb-odroidc2: switch ethernet phy mode to rgmii-txid

Quoted 21 lines · Heiner Kallweit

Documentation/networking/phy.txt states:
Whenever possible,use the PHY side RGMII delay.
The board uses a RTl8211F phy which supports creating the needed tx delay internally. Therefore switch to rgmii-txid mode.
Signed-off-by Heiner Kallweit <[email protected]>
---
?arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts | 1 + ?1 file changed, 1 insertion(+)
arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts +1 -0
index 3877dda6..94896139 100644
@@ -152,6 +152,7 @@
 ?	pinctrl-0 = <&eth_rgmii_pins>;
 ?	pinctrl-names = "default";
 ?	phy-handle = <&eth_phy0>;
+	phy-mode = "rgmii-txid";

Quoted 3 lines

?
? mdio {
? compatible = "snps,dwmac-mdio";

Heiner,

In principle, I agree with this patch but:

* We need the patches [0] [1] from net-next to merged first (or pulled in kevin's tree). Without this, the proposed change would result in a 4ns Tx delay instead of 2ns. If Martin send another version of patch [2], then "amlogic,tx-delay-ns = <2>;" should be removed for the odroidc2 as the delay would be introduced by the PHY (the value would ignored anyway, but it would be misleading)

* We would be changing a configuration tested by many people for a barely tested one, without any benefits expected. These 2 configurations are supposed to be equivalent, and I'm willing to test it again once the prerequisites are merged but I'd prefer if more people could test this and confirm there is no regression before merging it.

Cheers

Jerome

[0]: commit b765234e72fc ("net: stmmac: dwmac-meson8b: make the RGMII TX delay configurable")
[1]: commit d6db61a40ee0 ("net: stmmac: don't set tx delay in RGMII_ID and RGMII_TXID mode")
[2]: https://marc.info/?l=linux-arm-kernel&m=148754182813497&w=2

Heiner Kallweit

author

2017-03-02 19:37 UTC #2 lore raw

PATCH 1/1 ARM64: dts: meson-gxbb-odroidc2: switch ethernet phy mode to rgmii-txid

Am 02.03.2017 um 11:22 schrieb Jerome Brunet:

Quoted 28 lines · Heiner Kallweit

Quoted 17 lines
Documentation/networking/phy.txt states:
Whenever possible,use the PHY side RGMII delay.
The board uses a RTl8211F phy which supports creating the needed tx delay internally. Therefore switch to rgmii-txid mode.
Signed-off-by Heiner Kallweit <[email protected]>
---
 arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts | 1 +
 1 file changed, 1 insertion(+)
arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts +0 -0
index 3877dda6..94896139 100644
arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts line 158
Quoted 7 lines
arch/arm64/boot/dts/amlogic/meson-gxbb-odroidc2.dts +1 -0
@@ -152,6 +152,7 @@
 	pinctrl-0 = <&eth_rgmii_pins>;
 	pinctrl-names = "default";
 	phy-handle = <&eth_phy0>;
+	phy-mode = "rgmii-txid";
 
 	mdio {
 		compatible = "snps,dwmac-mdio";
Heiner,

Quoted 9 lines

In principle, I agree with this patch but:
* We need the patches [0] [1] from net-next to merged first (or pulled in kevin's tree). Without this, the proposed change would result in a 4ns Tx delay instead of 2ns. If Martin send another version of patch [2], then "amlogic,tx-delay-ns = <2>;" should be removed for the odroidc2 as the delay would be introduced by the PHY (the value would ignored anyway, but it would be misleading)

Right ..

Quoted 7 lines

* We would be changing a configuration tested by many people for a barely tested one, without any benefits expected. These 2 configurations are supposed to be equivalent, and I'm willing to test it again once the prerequisites are merged but I'd prefer if more people could test this and confirm there is no regression before merging it.

Also right. There is no urgent need for this patch and I'm totally fine with waiting for more feedback.
It's just a minor improvement to make the configuration more in line with the documented best practices.

Heiner

Quoted 12 lines

Cheers
Jerome
[0]: commit b765234e72fc ("net: stmmac: dwmac-meson8b: make the RGMII TX delay configurable")
[1]: commit d6db61a40ee0 ("net: stmmac: don't set tx delay in RGMII_ID and RGMII_TXID mode")
[2]: https://marc.info/?l=linux-arm-kernel&m=148754182813497&w=2