[PATCH 4/5] ARM: dts: stm32: Add missing ETHCK clock to ethernet node

[Marek Vasut]

On 1/13/20 2:26 PM, Patrick DELAUNAY wrote:
> Hi Marek,

Hi,

> + Christophe (Maintainer in kernel)
> 
>> From: Marek Vasut <marex at denx.de>
>> Sent: vendredi 10 janvier 2020 01:29
>>
>> Add missing 'eth-ck' clock to the ethernet node. These clock are used to generate
>> external clock signal for the PHY in case 'st,eth_ref_clk_sel'
>> is specified.
>>
>> Signed-off-by: Marek Vasut <marex at denx.de>
>> Cc: Patrick Delaunay <patrick.delaunay at st.com>
>> Cc: Patrice Chotard <patrice.chotard at st.com>
>> ---
>>  arch/arm/dts/stm32mp157c.dtsi | 2 ++
>>  1 file changed, 2 insertions(+)
>>
>> diff --git a/arch/arm/dts/stm32mp157c.dtsi b/arch/arm/dts/stm32mp157c.dtsi index
>> 6c670cf9a3..41aea75213 100644
>> --- a/arch/arm/dts/stm32mp157c.dtsi
>> +++ b/arch/arm/dts/stm32mp157c.dtsi
>> @@ -1404,11 +1404,13 @@
>>  			clock-names = "stmmaceth",
>>  				      "mac-clk-tx",
>>  				      "mac-clk-rx",
>> +				      "eth-ck",
>>  				      "ethstp",
>>  				      "syscfg-clk";
>>  			clocks = <&rcc ETHMAC>,
>>  				 <&rcc ETHTX>,
>>  				 <&rcc ETHRX>,
>> +				 <&rcc ETHCK_K>,
>>  				 <&rcc ETHSTP>,
>>  				 <&rcc SYSCFG>;
>>  			st,syscon = <&syscfg 0x4>;
> 
> This clock is optional, not needed by default for STM32MP15x:
> this clock is used only for a specific case: Phy without quartz, for all the other case we don't need to switch on this clock.

That's the usecase here.

> Normally if it is the case, it should be done in board part, not in SOC device tree (is is the strategy chosen by kernel).
> Moreover stm32mp157c.dtsi is just a copy of the kernel one, so this patch also need to be accepted by Kernel Maintainers.
> 
> NB: if you are in the Phy without crytal 50MHz (rmii + "st,eth_ref_clk_sel" + "eth-ck"),
>        You should have also the associated pin in the device tree of the board :
> 
> +     <STM32_PINMUX('G', 8, AF2)>, /* ETH_RMII_ETHCK */

My PHY is _NOT_ connected to this pin, the output clock of the SoC are PA1.

> Christophe you can complete my answer if it is not enough clear.

I would expect that you should describe _all_ the clock which are routed
into the ethernet IP in the DT and if the driver doesn't need some of
those clock, the driver should just not enable such clock.