Re: [PATCH net-next 12/16] dt-bindings: net: dwmac: Add MTL Tx Queue properties constraints

[Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>]

On 13/03/2023 23:50, Serge Semin wrote:
> Currently none of the MTL Tx Queues QoS-related DT-properties have been
> equipped with the proper constraints meanwhile they can be specified at
> least based on the corresponding CSR field sizes or the DW (x|xG)MAC
> IP-core synthesize parameter constraints. Let's do that:
> + snps,tx-queues-to-use - number of Tx queues to utilise is limited with a
> number of available queues. DW MAC/GMAC: no queues, DW Eth QoS: <= 8, DW
> xGMAC: <= 16.
> + snps,weight - Tx Queue/Traffic Class quantum/weight utilised depending
> on enabled algorithm for the Data Center Bridging feature: DWRR (up to
> 0x1312D0 bytes to add to credit) or WFQ (up to 0x3FFF - least bandwidth)
> or WFQ (up to 0x64). DW MAC/GMAC: no queues, DW Eth QoS: <= 0x1312D0, DW
> xGMAC: <= 0x1312D0.
> + snps,send_slope - Tx Queue/Traffic Class Send-Slope credit value
> subtracted from the accumulated credit for the Audio/Video bridging
> feature (CBS algorithm, bits per cycle scaled up by 1,024). DW MAC/GMAC:
> no queues, DW Eth QoS: <= 0x2000, DW xGMAC: <= 0x3FFF.
> + snps,idle_slope - same meaning as snps,send_slope except it's determines
> the Idle-Slope credit of CBS algorithm. DW MAC/GMAC: no queues, DW Eth
> QoS: <= 0x2000, DW xGMAC: <= 0x8000.
> + snps,high_credit/snps,low_credit - maximum and minimum values
> accumulated in the credit for the Audio/Video bridging feature (CBS
> algorithm, bits scaled up by 1,024). DW MAC/GMAC: no queues, DW Eth
> QoS: <= 0x1FFFFFFF, DW xGMAC: <= 0x1FFFFFFF.
> + snps,priority - Tx Queue/Traffic Class priority (enabled by the
> PFC-packets) limits determined by the VLAN tag PRI field width (it's 7).
> DW MAC/GMAC: no queues, DW Eth QoS: 0xff, DW xGMAC: 0xff.
> 
> Since the constraints vary for different IP-cores and the DT-schema is
> common for all of them the least restrictive values are chosen. The info
> above can be used for the IP-core specific DT-schemas if anybody ever is
> bothered with one to create.
> 
> Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
> ---
>  .../bindings/net/snps,dwmac-generic.yaml      |  2 +-
>  .../devicetree/bindings/net/snps,dwmac.yaml   | 24 ++++++++++++++++++-
>  2 files changed, 24 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/net/snps,dwmac-generic.yaml b/Documentation/devicetree/bindings/net/snps,dwmac-generic.yaml
> index ae740a1ab213..2974af79511d 100644
> --- a/Documentation/devicetree/bindings/net/snps,dwmac-generic.yaml
> +++ b/Documentation/devicetree/bindings/net/snps,dwmac-generic.yaml
> @@ -137,7 +137,7 @@ examples:
>                  snps,send_slope = <0x1000>;
>                  snps,idle_slope = <0x1000>;
>                  snps,high_credit = <0x3E800>;
> -                snps,low_credit = <0xFFC18000>;
> +                snps,low_credit = <0x1FC18000>;
>                  snps,priority = <0x1>;
>              };
>          };
> diff --git a/Documentation/devicetree/bindings/net/snps,dwmac.yaml b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
> index e5662b1498b7..2ebf7995426b 100644
> --- a/Documentation/devicetree/bindings/net/snps,dwmac.yaml
> +++ b/Documentation/devicetree/bindings/net/snps,dwmac.yaml
> @@ -250,6 +250,10 @@ properties:
>        snps,tx-queues-to-use:
>          $ref: /schemas/types.yaml#/definitions/uint32
>          description: number of TX queues to be used in the driver
> +        default: 1
> +        minimum: 1
> +        maximum: 16
> +
>        snps,tx-sched-wrr:
>          type: boolean
>          description: Weighted Round Robin
> @@ -296,13 +300,16 @@ properties:
>              snps,tx-sched-wfq: false
>              snps,tx-sched-dwrr: false
>      patternProperties:
> -      "^queue[0-9]$":
> +      "^queue([0-9]|1[0-5])$":
>          description: Each subnode represents a queue.
>          type: object
>          properties:
>            snps,weight:
>              $ref: /schemas/types.yaml#/definitions/uint32
>              description: TX queue weight (if using a DCB weight algorithm)
> +            minimum: 0
> +            maximum: 0x1312D0
> +
>            snps,dcb-algorithm:
>              type: boolean
>              description: TX queue will be working in DCB
> @@ -315,15 +322,27 @@ properties:
>            snps,send_slope:
>              $ref: /schemas/types.yaml#/definitions/uint32
>              description: enable Low Power Interface
> +            minimum: 0
> +            maximum: 0x3FFF

lowercase hex everywhere.

Best regards,
Krzysztof