Re: [PATCH v2 2/5] dt-bindings: net: add schema for NXP S32CC dwmac glue driver

["Andreas Färber" <afaerber@suse.de>]

Hi Krysztof,

Am 30.11.22 um 16:51 schrieb Krzysztof Kozlowski:
> On 28/11/2022 06:49, Chester Lin wrote:
>> Add the DT schema for the DWMAC Ethernet controller on NXP S32 Common
>> Chassis.
>>
>> Signed-off-by: Jan Petrous <jan.petrous@nxp.com>
>> Signed-off-by: Chester Lin <clin@suse.com>
> 
> Thank you for your patch. There is something to discuss/improve.
> 
>> ---
>>
>> Changes in v2:
>>    - Fix schema issues.
>>    - Add minItems to clocks & clock-names.
>>    - Replace all sgmii/SGMII terms with pcs/PCS.
>>
>>   .../bindings/net/nxp,s32cc-dwmac.yaml         | 135 ++++++++++++++++++
>>   1 file changed, 135 insertions(+)
>>   create mode 100644 Documentation/devicetree/bindings/net/nxp,s32cc-dwmac.yaml
>>
>> diff --git a/Documentation/devicetree/bindings/net/nxp,s32cc-dwmac.yaml b/Documentation/devicetree/bindings/net/nxp,s32cc-dwmac.yaml
>> new file mode 100644
>> index 000000000000..c6839fd3df40
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/net/nxp,s32cc-dwmac.yaml
[...]
>> +properties:
>> +  compatible:
>> +    enum:
>> +      - nxp,s32cc-dwmac
>> +
>> +  reg:
>> +    items:
>> +      - description: Main GMAC registers
>> +      - description: S32 MAC control registers
>> +
>> +  dma-coherent: true
>> +
>> +  clocks:
>> +    minItems: 5
> 
> Why only 5 clocks are required? Receive clocks don't have to be there?
> Is such system - only with clocks for transmit - usable?
> 
>> +    items:
>> +      - description: Main GMAC clock
>> +      - description: Peripheral registers clock
>> +      - description: Transmit PCS clock
>> +      - description: Transmit RGMII clock
>> +      - description: Transmit RMII clock
>> +      - description: Transmit MII clock
>> +      - description: Receive PCS clock
>> +      - description: Receive RGMII clock
>> +      - description: Receive RMII clock
>> +      - description: Receive MII clock
>> +      - description:
>> +          PTP reference clock. This clock is used for programming the
>> +          Timestamp Addend Register. If not passed then the system
>> +          clock will be used.
>> +
>> +  clock-names:
>> +    minItems: 5
>> +    items:
>> +      - const: stmmaceth
>> +      - const: pclk
>> +      - const: tx_pcs
>> +      - const: tx_rgmii
>> +      - const: tx_rmii
>> +      - const: tx_mii
>> +      - const: rx_pcs
>> +      - const: rx_rgmii
>> +      - const: rx_rmii
>> +      - const: rx_mii
>> +      - const: ptp_ref
>> +
>> +  tx-fifo-depth:
>> +    const: 20480
>> +
>> +  rx-fifo-depth:
>> +    const: 20480
>> +
>> +required:
>> +  - compatible
>> +  - reg
>> +  - tx-fifo-depth
>> +  - rx-fifo-depth
>> +  - clocks
>> +  - clock-names
>> +
>> +unevaluatedProperties: false
>> +
>> +examples:
>> +  - |
>> +    #include <dt-bindings/interrupt-controller/arm-gic.h>
>> +    #include <dt-bindings/interrupt-controller/irq.h>
>> +
>> +    #define S32GEN1_SCMI_CLK_GMAC0_AXI
>> +    #define S32GEN1_SCMI_CLK_GMAC0_TX_PCS
>> +    #define S32GEN1_SCMI_CLK_GMAC0_TX_RGMII
>> +    #define S32GEN1_SCMI_CLK_GMAC0_TX_RMII
>> +    #define S32GEN1_SCMI_CLK_GMAC0_TX_MII
>> +    #define S32GEN1_SCMI_CLK_GMAC0_RX_PCS
>> +    #define S32GEN1_SCMI_CLK_GMAC0_RX_RGMII
>> +    #define S32GEN1_SCMI_CLK_GMAC0_RX_RMII
>> +    #define S32GEN1_SCMI_CLK_GMAC0_RX_MII
>> +    #define S32GEN1_SCMI_CLK_GMAC0_TS
> 
> Why defines? Your clock controller is not ready? If so, just use raw
> numbers.

Please compare v1: There is no Linux-driven clock controller here but 
rather a fluid SCMI firmware interface. Work towards getting clocks into 
a kernel-hosted .dtsi was halted in favor of (downstream) TF-A, which 
also explains the ugly examples here and for pinctrl.

Logically there are only 5 input clocks; however due to SCMI not 
supporting re-parenting today, some clocks got duplicated at SCMI level. 
Andrew appeared to approve of that approach. I still dislike it but 
don't have a better proposal that would work today. So the two values 
above indeed seem wrong and should be 11 rather than 5.

Cheers,
Andreas

>> +
>> +    soc {
>> +      #address-cells = <1>;
>> +      #size-cells = <1>;
>> +
>> +      gmac0: ethernet@4033c000 {
>> +        compatible = "nxp,s32cc-dwmac";
>> +        reg = <0x4033c000 0x2000>, /* gmac IP */
>> +              <0x4007C004 0x4>;    /* S32 CTRL_STS reg */
> 
> Lowercase hex.
> 
>> +        interrupt-parent = <&gic>;
>> +        interrupts = <GIC_SPI 57 IRQ_TYPE_LEVEL_HIGH>;
>> +        interrupt-names = "macirq";
>> +        phy-mode = "rgmii-id";
>> +        tx-fifo-depth = <20480>;
>> +        rx-fifo-depth = <20480>;
>> +        dma-coherent;
>> +        clocks = <&clks S32GEN1_SCMI_CLK_GMAC0_AXI>,
>> +                 <&clks S32GEN1_SCMI_CLK_GMAC0_AXI>,
>> +                 <&clks S32GEN1_SCMI_CLK_GMAC0_TX_PCS>,
>> +                 <&clks S32GEN1_SCMI_CLK_GMAC0_TX_RGMII>,
>> +                 <&clks S32GEN1_SCMI_CLK_GMAC0_TX_RMII>,
>> +                 <&clks S32GEN1_SCMI_CLK_GMAC0_TX_MII>,
>> +                 <&clks S32GEN1_SCMI_CLK_GMAC0_RX_PCS>,
>> +                 <&clks S32GEN1_SCMI_CLK_GMAC0_RX_RGMII>,
>> +                 <&clks S32GEN1_SCMI_CLK_GMAC0_RX_RMII>,
>> +                 <&clks S32GEN1_SCMI_CLK_GMAC0_RX_MII>,
>> +                 <&clks S32GEN1_SCMI_CLK_GMAC0_TS>;
> 
> 
> Best regards,
> Krzysztof
> 

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