Re: [RFC PATCH 1/3] dt-bindings: net: sparx5: Add sparx5-switch bindings

[Steen Hegelund <steen.hegelund@microchip.com>]

On 27.11.2020 18:00, Andrew Lunn wrote:
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>> +  reg-names:
>> +    minItems: 153
>> +    items:
>> +      - const: dev2g5_0
>> +      - const: dev5g_0
>> +      - const: pcs5g_br_0
>> +      - const: dev2g5_1
>> +      - const: dev5g_1
>...
>> +      - const: ana_ac
>> +      - const: vop
>
>> +    switch: switch@600000000 {
>> +      compatible = "microchip,sparx5-switch";
>> +      reg = <0x10004000 0x4000>, /* dev2g5_0 */
>> +        <0x10008000 0x4000>, /* dev5g_0 */
>> +        <0x1000c000 0x4000>, /* pcs5g_br_0 */
>> +        <0x10010000 0x4000>, /* dev2g5_1 */
>> +        <0x10014000 0x4000>, /* dev5g_1 */
>
>...
>
>> +        <0x11800000 0x100000>, /* ana_l2 */
>> +        <0x11900000 0x100000>, /* ana_ac */
>> +        <0x11a00000 0x100000>; /* vop */
>
>This is a pretty unusual binding.
>
>Why is it not
>
>reg = <0x10004000 0x1af8000>
>
>and the driver can then break up the memory into its sub ranges?
>
>    Andrew
Hi Andrew,

Since the targets used by the driver is not always in the natural
address order (e.g. the dev2g5_x targets), I thought it best to let the DT
take care of this since this cannot be probed.  I am aware that this causes
extra mappings compared to the one-range strategy, but this layout seems more
transparent to me, also when mapped over PCIe.


BR
Steen


---------------------------------------
Steen Hegelund
steen.hegelund@microchip.com