diff mbox series

[v2,4/8] arm64: dts: qcom: sa8775p-ride: move the reset-gpios property of the PHY

Message ID 20230808190144.19999-5-brgl@bgdev.pl (mailing list archive)
State Superseded
Headers show
Series arm64: dts: qcom: enable EMAC1 on sa8775p | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch

Commit Message

Bartosz Golaszewski Aug. 8, 2023, 7:01 p.m. UTC 
From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>

Device-tree bindings for MDIO define per-PHY reset-gpios as well as a
global reset-gpios property at the MDIO node level which controls all
devices on the bus. The latter is most likely a workaround for the
chicken-and-egg problem where we cannot read the ID of the PHY before
bringing it out of reset but we cannot bring it out of reset until we've
read its ID.

I have proposed a comprehensive solution for this problem in 2020 but it
never got upstream. We do however have workaround in place which allows
us to hard-code the PHY id in the compatible property, thus skipping the
ID scanning.

Let's make the device-tree for sa8775p-ride slightly more correct by
moving the reset-gpios property to the PHY node with its ID put into the
PHY node's compatible.

Link: https://lore.kernel.org/all/20200622093744.13685-1-brgl@bgdev.pl/
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
---
 arch/arm64/boot/dts/qcom/sa8775p-ride.dts | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

Comments

Konrad Dybcio Aug. 8, 2023, 9:09 p.m. UTC | #1 
On 8.08.2023 21:01, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> Device-tree bindings for MDIO define per-PHY reset-gpios as well as a
> global reset-gpios property at the MDIO node level which controls all
> devices on the bus. The latter is most likely a workaround for the
> chicken-and-egg problem where we cannot read the ID of the PHY before
> bringing it out of reset but we cannot bring it out of reset until we've
> read its ID.
> 
> I have proposed a comprehensive solution for this problem in 2020 but it
> never got upstream. We do however have workaround in place which allows
> us to hard-code the PHY id in the compatible property, thus skipping the
> ID scanning.
> 
> Let's make the device-tree for sa8775p-ride slightly more correct by
> moving the reset-gpios property to the PHY node with its ID put into the
> PHY node's compatible.
> 
> Link: https://lore.kernel.org/all/20200622093744.13685-1-brgl@bgdev.pl/
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> ---
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>

Konrad
diff mbox series

Patch

diff --git a/arch/arm64/boot/dts/qcom/sa8775p-ride.dts b/arch/arm64/boot/dts/qcom/sa8775p-ride.dts
index 09ae6e153282..a03a4c17c8f0 100644
--- a/arch/arm64/boot/dts/qcom/sa8775p-ride.dts
+++ b/arch/arm64/boot/dts/qcom/sa8775p-ride.dts
@@ -279,13 +279,13 @@  mdio {
 		#address-cells = <1>;
 		#size-cells = <0>;
 
-		reset-gpios = <&pmm8654au_2_gpios 8 GPIO_ACTIVE_LOW>;
-		reset-delay-us = <11000>;
-		reset-post-delay-us = <70000>;
-
 		sgmii_phy: phy@8 {
+			compatible = "ethernet-phy-id0141.0dd4";
 			reg = <0x8>;
 			device_type = "ethernet-phy";
+			reset-gpios = <&pmm8654au_2_gpios 8 GPIO_ACTIVE_LOW>;
+			reset-assert-us = <11000>;
+			reset-deassert-us = <70000>;
 		};
 	};