From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [RFC V4 0/3] arm_pmu: acpi: variant support and QCOM Falkor extensions
Date: Wed, 25 Jul 2018 16:16:41 +0100 [thread overview]
Message-ID: <20180725151641.GC6866@arm.com> (raw)
In-Reply-To: <CAGbRU0QLSpNEtcryuPPZE98zAo7peEmcDqcQiLi1zO6cfKML2A@mail.gmail.com>
On Sun, Jul 15, 2018 at 03:35:45PM -0500, J. Agust?n Vega-Fr?as wrote:
> On Fri, Jul 13, 2018 at 10:33 AM, Will Deacon <will.deacon@arm•com> wrote:
> > I'm mostly ok with this approach, but I have a concern with the way in which
> > the sysfs interface for carving up the config fields is implemented. If this
> > is intended to be a strict extension to the armv8 pmu architecture, then I
> > don't think you should be overriding the attr_groups entirely. Rather, you
> > should be taking the attr_groups from pmuv3 and then extending them in a way
> > which avoids overlapping field allocations by construction.
> >
> > As it stands, you already have an overlap between the pcc bit and the
> > chained counter bit which Suzuki has implemented and it will be very easy to
> > introduce API breakage if we don't enforce this as part of the design.
> >
> > Will
>
> FYI, I left Qualcomm on July 6, one of my former colleagues will submit
> new iterations of this series. I will continue to comment on this and future
> patchsets as a courtesy to my former colleagues and the community.
>
> Thanks for pointing out the sysfs issue. My suggestion on how to address it is:
>
> 1. Reserve config and config1 for architectural format attributes and
> config2 for extension format attributes.
> 2. Add a struct attribute ** parameter to the extension init function so
> extensions can return the new attributes.
> 3. The extension framework code in arm_pmu_acpi.c can then allocate a new
> attribute array to contain the base and extension attributes and ensure
> all the new attributes are on config2.
>
> Though a more elaborate approach can be implemented to find conflicts in
> bit usage within config fields, it would require much more code for a
> relatively simple problem. Thoughts?
As long as you're happy to live inside config2, that sounds sensible to me.
Will
prev parent reply other threads:[~2018-07-25 15:16 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-05 20:23 [RFC V4 0/3] arm_pmu: acpi: variant support and QCOM Falkor extensions Agustin Vega-Frias
2018-07-05 20:23 ` [RFC V4 1/4] ACPI: add support for sentinel-delimited probe tables Agustin Vega-Frias
2018-07-05 20:23 ` [RFC V4 2/4] arm_pmu: acpi: add support for CPU PMU variant detection Agustin Vega-Frias
2018-07-05 20:23 ` [RFC V4 3/4] perf: qcom: Add PC capture support to CPU PMU Agustin Vega-Frias
2018-07-05 20:23 ` [RFC V4 4/4] perf: qcom: Add Falkor CPU PMU IMPLEMENTATION DEFINED event support Agustin Vega-Frias
2018-07-13 15:33 ` [RFC V4 0/3] arm_pmu: acpi: variant support and QCOM Falkor extensions Will Deacon
2018-07-15 20:35 ` J. Agustín Vega-Frías
2018-07-25 15:16 ` Will Deacon [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180725151641.GC6866@arm.com \
--to=will.deacon@arm$(echo .)com \
--cc=linux-arm-kernel@lists$(echo .)infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox