From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Ulf Hansson <ulf.hansson@linaro.org>
Cc: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
Linux PM list <linux-pm@vger.kernel.org>,
Bjorn Andersson <bjorn.andersson@linaro.org>,
Stephen Boyd <sboyd@kernel.org>,
Saravana Kannan <saravanak@google.com>,
Dmitry Baryshkov <dmitry.baryshkov@linaro.org>,
Kevin Hilman <khilman@kernel.org>,
Geert Uytterhoeven <geert+renesas@glider.be>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] PM: domains: Don't attach a device to genpd that corresponds to a provider
Date: Fri, 9 Jul 2021 15:57:56 +0200 [thread overview]
Message-ID: <CAMuHMdW8f0YGwNBAzwG65OE+Wq59SqUFmHhDPE0Nju7OpDzLYA@mail.gmail.com> (raw)
In-Reply-To: <CAPDyKFo8SCbmJXQJJ4OR8_Tg=+YdK76k2Sg=KcO3t7ve2zzaHw@mail.gmail.com>
Hi Ulf,
On Fri, Jul 9, 2021 at 3:48 PM Ulf Hansson <ulf.hansson@linaro.org> wrote:
> On Fri, 9 Jul 2021 at 15:35, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Fri, Jul 9, 2021 at 3:23 PM Ulf Hansson <ulf.hansson@linaro.org> wrote:
> > > On Fri, 9 Jul 2021 at 15:07, Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > > > On Fri, Jul 9, 2021 at 2:56 PM Ulf Hansson <ulf.hansson@linaro.org> wrote:
> > > > > According to the common power domain DT bindings, a power domain provider
> > > > > must have a "#power-domain-cells" property in its OF node. Additionally, if
> > > > > a provider has a "power-domains" property, it means that it has a parent
> > > > > domain.
> > > >
> > > > OK.
> > > >
> > > > > It has turned out that some OF nodes that represents a genpd provider may
> > > > > also be compatible with a regular platform device. This leads to, during
> > > > > probe, genpd_dev_pm_attach(), genpd_dev_pm_attach_by_name() and
> > > > > genpd_dev_pm_attach_by_id() tries to attach the corresponding struct device
> > > > > to the genpd provider's parent domain, which is wrong. Instead the genpd
> > > >
> > > > Why is that wrong?
> > >
> > > It may lead to that the struct device that corresponds to a genpd
> > > provider may be attached to the parent domain. In other words, the
> > > parent domain will not only be controlled by a child domain
> > > (corresponding to the provider), but also through the provider's
> > > struct device. As far as I can tell, this has never been the intent
> > > for how things should work in genpd.
> >
> > Ah, you're worried about the case where the subdomain is a child of
> > the parent domain, but the actual subdomain controller (represented
> > by the platform device) isn't?
>
> Well, even if the platform device represents a subdomain controller,
> should it really be attached to the parent domain?
That's what the presence of the "power-domains" property means,
isn't it?
If the subdomain controller itself is not part of the parent power
domain, there should not be a "power-domains" property. So perhaps
we need a new property ("power-domain-parent"?) to indicate what is
the parent domain for the subdomains in this case?
> In any case, it means that the provider needs to manage runtime PM,
> etc for its struct device to not prevent the parent domain from being
> powered off.
Shouldn't all drivers for devices that can be somewhere in a PM Domain
hierarchy do that anyway? :-) See e.g. commit 3a611e26e958b037
("net/smsc911x: Add minimal runtime PM support").
If "simple-bus" would do that, we could get rid of "simple-pm-bus"...
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
next prev parent reply other threads:[~2021-07-09 13:58 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-09 12:56 [PATCH] PM: domains: Don't attach a device to genpd that corresponds to a provider Ulf Hansson
2021-07-09 13:06 ` Geert Uytterhoeven
2021-07-09 13:22 ` Ulf Hansson
2021-07-09 13:35 ` Geert Uytterhoeven
2021-07-09 13:48 ` Ulf Hansson
2021-07-09 13:57 ` Geert Uytterhoeven [this message]
2021-07-09 14:02 ` Ulf Hansson
2021-07-09 13:46 ` Bjorn Andersson
2021-07-09 13:58 ` Ulf Hansson
2021-07-09 14:16 ` Bjorn Andersson
2021-07-09 18:49 ` kernel test robot
2021-07-09 19:01 ` kernel test robot
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=CAMuHMdW8f0YGwNBAzwG65OE+Wq59SqUFmHhDPE0Nju7OpDzLYA@mail.gmail.com \
--to=geert@linux-m68k.org \
--cc=bjorn.andersson@linaro.org \
--cc=dmitry.baryshkov@linaro.org \
--cc=geert+renesas@glider.be \
--cc=khilman@kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=rjw@rjwysocki.net \
--cc=saravanak@google.com \
--cc=sboyd@kernel.org \
--cc=ulf.hansson@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
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;
as well as URLs for NNTP newsgroup(s).