Re: [PATCH 7/8] arm64: dts: qcom: ipq5018: enable ethernet support

From: Ziyang Huang <hzyitc@outlook.com>
To: Andrew Lunn <andrew@lunn.ch>
Cc: mcoquelin.stm32@gmail.com, alexandre.torgue@foss.st.com,
	richardcochran@gmail.com, p.zabel@pengutronix.de,
	matthias.bgg@gmail.com, angelogioacchino.delregno@collabora.com,
	linux-kernel@vger.kernel.org,
	linux-stm32@st-md-mailman.stormreply.com,
	linux-arm-kernel@lists.infradead.org, netdev@vger.kernel.org,
	linux-mediatek@lists.infradead.org
Subject: Re: [PATCH 7/8] arm64: dts: qcom: ipq5018: enable ethernet support
Date: Mon, 22 Jan 2024 23:52:30 +0800	[thread overview]
Message-ID: <TYZPR01MB5556603EA4C5D7BAF9C27C6AC9752@TYZPR01MB5556.apcprd01.prod.exchangelabs.com> (raw)
In-Reply-To: <b8510b38-3669-4a04-9ca6-dbe937ecbec3@lunn.ch>

在 2024/1/22 0:45, Andrew Lunn 写道:
> On Sun, Jan 21, 2024 at 08:42:36PM +0800, Ziyang Huang wrote:
>> Signed-off-by: Ziyang Huang <hzyitc@outlook.com>
>> ---
>>   arch/arm64/boot/dts/qcom/ipq5018.dtsi | 120 +++++++++++++++++++++++++-
>>   1 file changed, 116 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/arm64/boot/dts/qcom/ipq5018.dtsi b/arch/arm64/boot/dts/qcom/ipq5018.dtsi
>> index e502a3ecf4b7..b36e5c2136b7 100644
>> --- a/arch/arm64/boot/dts/qcom/ipq5018.dtsi
>> +++ b/arch/arm64/boot/dts/qcom/ipq5018.dtsi
>> @@ -94,6 +94,63 @@ soc: soc@0 {
>>   		#size-cells = <1>;
>>   		ranges = <0 0 0 0xffffffff>;
>>   
>> +		mdio0: mdio@88000 {
>> +			#address-cells = <1>;
>> +			#size-cells = <0>;
>> +			compatible = "qcom,ipq5018-mdio", "qcom,qca-mdio";
>> +			reg = <0x88000 0x64>;
>> +			resets = <&gcc GCC_GEPHY_MDC_SW_ARES>,
>> +				 <&gcc GCC_GEPHY_DSP_HW_ARES>;
> 
> What do these two resets do? An MDIO bus controller is unlikely to
> have a DSP in it. That is something a PHY is more likely to have. An
> MDIO bus controller does have an MDC line, but why is it
> GCC_GEPHY_MDC_SW_ARES not GCC_MDIO_MDC_SW_ARES? So this again makes me
> think this is a PHY reset, so should be in the PHY node.
> 

IPQ5018 has two mdio bus. mdio0 is an internal bus which only connects 
to internal PHY while mdio1 is outgoing and can be used to connect PHY 
or switch.

So I thought GCC_GEPHY_MDC_SW_ARES is for mdio0 and GCC_MDIO_MDC_SW_ARES 
is for mdio1.

GCC_GEPHY_DSP_HW_ARES is seem like PHY reset. But if we don't deassert 
it, the phy node can't be scaned. So I add it here like what reset-gpios 
do - to reset PHY or switch.

> A device tree binding will help sort this out.

Base on the functions I explained, I can't write the accurate names and 
number of resets here.

> 
> 
>      Andrew
> 
> ---
> pw-bot: cr