Re: [PATCH v3 3/8] iommu/riscv: Add HPM support for performance monitoring

Zong Li
2026-02-07T02:12:04Z

On Fri, Feb 6, 2026 at 11:09 PM Andrew Jones
<andrew.jones@oss.qualcomm.com> wrote:
>
> On Fri, Feb 06, 2026 at 11:42:39AM +0800, Lv Zheng wrote:
> > On 2/5/2026 11:23 PM, Andrew Jones wrote:
> ...
> > > Since Zong Li's patches were already on the list then your serieswould> at
> > least discuss them in the cover letter, explaining why you've opted
> > > not to adopt them. But, most likely some of the patches can be adopted,
> > > so those should be extracted from Zong Li's work (with authorship
> > > preserved) and based upon in order to respect that prior work.
> > >
> >
> > You can see we have contacted each other in community, and decided to
> > cooperate in this way to honor his contribution. But final decision is
> > left for the community to decide:
> >
> > From Zong Li:
> > >> Of course, if the community would prefer to go your version, I’m
> > >> perfectly fine with that as well.
> >
> > We respect all contributions, We'll add the link in cover letter to the
> > follow-up revisions, let me know if anything else should be done to the
> > new revisions.
>
> Just do all the communication before posting, allowing that communication
> to be summarized in the cover letter and in any appropriate commit
> messages so reviewers know what's going on. Also don't forget to CC
> anybody previously involved to ensure they have a chance to chime in.
>
> >
> > --------------------------------------------------------------------
> >
> > And let me describe in details to compare the functionalities and
> > addressed comments between what is provided by Joey and by Zong:
> >
> > https://lore.kernel.org/all/20250115030306.29735-1-zong.li@sifive.com/
> >
> > There is no missing functionalities between the two approaches, I also
> > checked the original Robin's comments, let me describe them in details:
>
> My concern wasn't whether or not Robin's comments were addressed in this
> posting (that's important, but not what I'm talking about). My concern
> was that Zong Li's work wasn't addressed in any way, so appeared to be
> a chance for duplicated efforts. Indeed his reply [1] indicates exactly
> that and even that there is a third patch series being worked
> independently. Please work out who and what patches are going to be
> the focus going forward and describe that decision in the cover letter
> for the next revision. And please don't forget to CC Zong Li and Yaxing
> Guo.
>
> [1] https://lore.kernel.org/all/CANXhq0oi9nE7ffLGsz5j8GnC1UDTD-4bE4cantRjW2fXHYrjHA@mail.gmail.com/
>

First of all, I apologize for the delay of the PMU series and any
inconvenience it may have caused. I also really appreciate Andrew for
pointing out the upstream culture and consensus.

My next version (v3 series) is expected to be sent out in the next
couple of days. It will pick up all the suggestions and feedback from
the previous versions. Apart from that, the main structural change is
that the PMU driver has been moved under drivers/perf/, which is
something that has been mentioned repeatedly by several people.

To allow everyone to review the major changes in the next version as
soon as possible, the custom event support will be split into a
separate series. Its overall idea will be similar to a typical
platform driver, where vendor-specific PMU events are defined through
driver data. More details will be described in the v3 cover letter.

Additionally, since I did not follow up the patches from Lv Zheng,
Jingyu Li, or Yaxing, it is very possible that my v3 series may miss
some important features or fixes from their work. If that is the case,
I apologize, I was not aware that those patches had been posted to
the mailing list, which is also why I did not respond to their v1
patch series in a timely manner. Therefore, I would really appreciate
it if everyone could help review the v3 series and point out any
additional fixes or feature support that I may have missed.

I also really appreciate everyone for always helping to bring us
together and keep the discussions aligned.
Thanks

> Thanks,
> drew