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

Lad, Prabhakar
2022-11-25T18:18:59Z

Hi Krzysztof,

On Fri, Nov 25, 2022 at 12:12 PM Krzysztof Kozlowski
<krzysztof.kozlowski@linaro.org> wrote:
>
> 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.
>
I got your point. I'll make use of the header in the driver for the
next version and fix your previously pointed comments.

Cheers,
Prabhakar