From: Marek Vasut marex@denx.de
[ Upstream commit 1cebcf9932ab76102e8cfc555879574693ba8956 ]
The Microchip LAN8710Ai PHY requires XTAL1/CLKIN external clock to be enabled when the nRST is toggled according to datasheet Microchip LAN8710A/LAN8710Ai DS00002164B page 35 section 3.8.5.1 Hardware Reset: " A Hardware reset is asserted by driving the nRST input pin low. When driven, nRST should be held low for the minimum time detailed in Section 5.5.3, "Power-On nRST & Configuration Strap Timing," on page 59 to ensure a proper transceiver reset. During a Hardware reset, an external clock must be supplied to the XTAL1/CLKIN signal. " This is accidentally fulfilled in the current setup, where ETHCK_K is used to supply both PHY XTAL1/CLKIN and is also fed back through eth_clk_fb to supply ETHRX clock of the DWMAC. Hence, the DWMAC enables ETHRX clock, that has ETHCK_K as parent, so ETHCK_K clock are also enabled, and then the PHY reset toggles.
However, this is not always the case, e.g. in case the PHY XTAL1/CLKIN clock are supplied by some other clock source than ETHCK_K or in case ETHRX clock are not supplied by ETHCK_K. In the later case, ETHCK_K would be kept disabled, while ETHRX clock would be enabled, so the PHY would not be receiving XTAL1/CLKIN clock and the reset would fail.
Improve the DT by adding the PHY clock phandle into the PHY node, which then also requires moving the PHY reset GPIO specifier in the same place and that then also requires correct PHY reset GPIO timing, so add that too.
A brief note regarding the timing, the datasheet says the reset should stay asserted for at least 100uS and software should wait at least 200nS after deassertion. Set both delays to 500uS which should be plenty.
Fixes: 34e0c7847dcf ("ARM: dts: stm32: Add DH Electronics DHCOM STM32MP1 SoM and PDK2 board") Signed-off-by: Marek Vasut marex@denx.de Cc: Alexandre Torgue alexandre.torgue@st.com Cc: Patrice Chotard patrice.chotard@st.com Cc: Patrick Delaunay patrick.delaunay@st.com Cc: linux-stm32@st-md-mailman.stormreply.com To: linux-arm-kernel@lists.infradead.org Signed-off-by: Alexandre Torgue alexandre.torgue@foss.st.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi b/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi index 71f3e4efce65..27f19575fada 100644 --- a/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi +++ b/arch/arm/boot/dts/stm32mp15xx-dhcom-som.dtsi @@ -118,7 +118,6 @@ max-speed = <100>; phy-handle = <&phy0>; st,eth-ref-clk-sel; - phy-reset-gpios = <&gpioh 3 GPIO_ACTIVE_LOW>;
mdio0 { #address-cells = <1>; @@ -127,6 +126,13 @@
phy0: ethernet-phy@1 { reg = <1>; + /* LAN8710Ai */ + compatible = "ethernet-phy-id0007.c0f0", + "ethernet-phy-ieee802.3-c22"; + clocks = <&rcc ETHCK_K>; + reset-gpios = <&gpioh 3 GPIO_ACTIVE_LOW>; + reset-assert-us = <500>; + reset-deassert-us = <500>; interrupt-parent = <&gpioi>; interrupts = <11 IRQ_TYPE_LEVEL_LOW>; };