[PATCH 01/12] drivers/perf: arm_spe: Store event reserved bits in driver data

[Leo Yan]

On Thu, Jun 19, 2025 at 12:28:27PM +0100, James Clark wrote:

[...]

> > @@ -77,6 +77,7 @@ struct arm_spe_pmu {
> >   	u16					pmsver;
> >   	u16					min_period;
> >   	u16					counter_sz;
> > +	u64					pmsevfr_res0;
> 
> IMO this is a premature optimization and we shouldn't store things that are
> only transformations of some other already stored value. It becomes another
> thing to worry about when it's valid to read and to potentially keep it up
> to date etc.
> 
> It's just one new one now, but eventually you end up with tons of them and
> then someone forgets to update a dependent one when the parent value changes
> and it makes a mess.
> 
> And arm_spe_pmu_event_init() isn't even a particularly hot path.

Makes sense. I will drop this one.

Thanks for suggestions!

Leo