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

[Serge Semin]

On Thu, Mar 16, 2023 at 09:08:02AM +0100, Krzysztof Kozlowski wrote:
> 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@xxxxxxxxxxxxxxxxxxxx>
> > ---
> >  .../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.

Got it. Thanks.

-Serge(y)

> 
> Best regards,
> Krzysztof
>