RE: [EXT] Re: [PATCH 1/3] dt-bindings: perf: fsl-imx-ddr: Add i.MX95 compatible

Xu Yang
2023-12-06T01:42:55Z

Hi Hi Conor,

>
> On Fri, Dec 01, 2023 at 06:41:59AM +0000, Xu Yang wrote:
> > Hi Conor,
> >
> > >
> > > On Mon, Nov 27, 2023 at 03:32:06PM +0800, Xu Yang wrote:
> > > > i.MX95 has a more precise counting capability than i.MX93. This will add
> > > > a compatible for it.
> > >
> > > It is hard to tell from this comment, but I figure this "more precise
> > > capability" is not an option you can enable, but instead makes the
> > > programming model of this device different to that of the imx93?
> >
> > Actually, imx95 is compatible with imx93 except AXI ID filter capability.
> > But for AXI ID filter, imx95 is using different registers and bits from
> > imx93 for filter configuration.
>
> This sounds like it conflicts with...
>
> > To distinguish them, I need use different
> > compatible because programming model cannot recognize which device is
> > running.
> >
> > compatible = "fsl,imx95-ddr-pmu";
>
> > compatible = "fsl,imx95-ddr-pmu", "fsl,imx93-ddr-pmu";
>
> ...this. If drivers for the imx93 need changes to work on the imx95,
> then `compatible = "fsl,imx95-ddr-pmu", "fsl,imx93-ddr-pmu";` cannot be
> used. If they will work, with only the new imx95 features being
> non-functional, then you can use it.

Yes, it is. When compatible = "fsl,imx95-ddr-pmu", "fsl,imx93-ddr-pmu" is used,
only the new imx95 features is not functional, other basic function works for
both imx95 and imx93.

Thanks,
Xu Yang

>
> > Both above compatible is okay for me. Therefore, "fsl,imx95-ddr-pmu" is needed.