Re: [PATCH v4 6/7] dt-bindings: cache: r9a07g043f-l2-cache: Add DT binding documentation for L2 cache controller

Krzysztof Kozlowski
2022-11-25T12:12:29Z

On 25/11/2022 11:34, Lad, Prabhakar wrote:
>>> +/* Device, Non-bufferable */
>>> +#define AX45MP_PMACFG_MTYP_DEV_NON_BUF (0 << 2)
>>> +/* Device, bufferable */
>>> +#define AX45MP_PMACFG_MTYP_DEV_BUF (1 << 2)
>>> +/* Memory, Non-cacheable, Non-bufferable */
>>> +#define AX45MP_PMACFG_MTYP_MEM_NON_CACHE_NON_BUF (2 << 2)
>>> +/* Memory, Non-cacheable, Bufferable */
>>> +#define AX45MP_PMACFG_MTYP_MEM_NON_CACHE_BUF (3 << 2)
>>
>> What are all these? They don't look like flags, because 3 = 1 | 2...
>> they don't look like constants, because we do not use shifts in
>> constants. Are these some register values? I also do not see the header
>> being used in the code, so why having a bindings header if it is not
>> used (DTS is not usage...)?
>>
> These are register bit values for the MTYP[5:2] field. The DTS example
> in the binding doc (above) uses these macros. I haven't included the
> DTS/I patches with this patchset yet do think I should?

Then why storing it as bindings? Bindings headers describe the interface
implemented by drivers and used by DTS, but this is not implemented by
drivers.

Best regards,
Krzysztof