Re: [PATCH v6 07/11] drivers: perf: hisi: Add support for Hisilicon SoC event counters

[Anurup M]

On Friday 24 March 2017 05:27 PM, Mark Rutland wrote:
> > +/* hip05/06 chips L3C bank identifier */
> > >+static u32 l3c_bankid_map_v1[MAX_BANKS] = {
> > >+    0x02, 0x04, 0x01, 0x08,
> > >+};
> > >+
> > >+/* hip07 chip L3C bank identifier */
> > >+static u32 l3c_bankid_map_v2[MAX_BANKS] = {
> > >+    0x01, 0x02, 0x03, 0x04,
> > >+};
> > >
> > >Is my approach OK? or can be improved?
> I think it would make more sense for this to be described in the DT.

Ok. Shall describe it in DT.

> [...]
>
> > I shall handle the error internally and propagate it until a void
> > >function (pmu->start, pmu->stop, pmu->del etc. are void).
> > >e.g. in the scenario pmu->add ---> pmu->start. If start fail,
> > >pmu->add cannot catch it and continues.
> > >the counter index could be cleared when pmu->del is called later.
> > >
> > >Is this fine? Any suggestion to handle it?
> Propagating it up to a void function, only to silently fail is not good.
>
> Given it seems this should only happen if there is a major HW problem,
> I'd be happier with a BUG_ON() in the djtag accessors.

Yes, it occur only when major HQ problem. I would add BUG_ON in djtag 
and simplify callers.

> [...]
>
> > > > >In the absence of pmu::{enable,disable}, you must disallow groups, since
> > > > >their events will be enabled for different periods of time.
> > >
> > >For L3 cache and MN PMU, pmu::{enable,disable}is present. But in
> > >case of Hisilicon DDRC PMU,
> > >it is not available. It only support continuous counting. I shall
> > >disallow groups when adding support
> > >for DDRC PMU.
> Given this code does not currently support the DDRC, please simplify
> the coder to assume these callbacks always exist. We can alter it when
> DDRC support arrives.

Ok. Sure. Shall remove all similar checks added for DDRC in this file to 
simplify.

Thanks,
Anurup

> Thanks,
> Mark.