linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Tony Lindgren <tony@atomide.com>
To: Saravana Kannan <saravanak@google.com>
Cc: Abel Vesa <abelvesa@kernel.org>,
	Russell King <linux@armlinux.org.uk>,
	Neil Armstrong <narmstrong@baylibre.com>,
	Geert Uytterhoeven <geert+renesas@glider.be>,
	Magnus Damm <magnus.damm@gmail.com>,
	Catalin Marinas <catalin.marinas@arm.com>,
	Will Deacon <will@kernel.org>,
	Damien Le Moal <damien.lemoal@wdc.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Ulf Hansson <ulf.hansson@linaro.org>,
	Rob Herring <robh+dt@kernel.org>,
	kernel-team@android.com, linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, linux-oxnas@groups.io,
	linux-renesas-soc@vger.kernel.org, linux-omap@vger.kernel.org,
	linux-riscv@lists.infradead.org
Subject: Re: [PATCH v4 1/2] drivers: bus: simple-pm-bus: Add support for probing simple bus only devices
Date: Tue, 16 Nov 2021 07:19:43 +0200	[thread overview]
Message-ID: <YZM/b2/F8xmK43vr@atomide.com> (raw)
In-Reply-To: <CAGETcx_a-d7qQNi3sUce3AzbPcvGJK5JSuiiHm4h4e_q-MT7Dg@mail.gmail.com>

* Saravana Kannan <saravanak@google.com> [211115 20:19]:
> On Wed, Nov 10, 2021 at 12:24 PM Saravana Kannan <saravanak@google.com> wrote:
> >
> > On Wed, Nov 10, 2021 at 4:16 AM Abel Vesa <abelvesa@kernel.org> wrote:
> > >
> > > On 21-09-28 17:07:33, Saravana Kannan wrote:
> > > > fw_devlink could end up creating device links for bus only devices.
> > > > However, bus only devices don't get probed and can block probe() or
> > > > sync_state() [1] call backs of other devices. To avoid this, probe these
> > > > devices using the simple-pm-bus driver.
> > > >
> > > > However, there are instances of devices that are not simple buses (they get
> > > > probed by their specific drivers) that also list the "simple-bus" (or other
> > > > bus only compatible strings) in their compatible property to automatically
> > > > populate their child devices. We still want these devices to get probed by
> > > > their specific drivers. So, we make sure this driver only probes devices
> > > > that are only buses.
...
> > >
> > > This change is breaking the expected behavior for the already existent
> > > simple-bus nodes. All the simple-bus compatibles should be replaced now
> > > to simple-pm-bus. In my case, on some i.MX8 platforms, without the
> > > devlink, the devices suspend sequence changes (and even breaks).
> > >
> > > To avoid breaking the already existent simple-bus nodes, maybe the logic
> > > should've been reversed: keep the simple-bus as is and add another
> > > compatible, IDK, something like simple-trasnparent-bus, or something.
> >
> > The intent of this change IS to affect existing simple-bus nodes (but
> > not in the way it's affecting you). But if it's breaking stuff, we
> > obviously need to fix it.
> >
> > I have a hunch on what's going on in your case, but can you point me
> > to the specific simple-bus node that's getting affected? I'm expecting
> > it to be a simple-bus node that gets added AFTER this driver is
> > registered at device_initcall (module_init gets converted to
> > device_initcall).
> >
> > Also, can you try this hack patch to see if it helps your case?
> > https://lore.kernel.org/lkml/CAGETcx9U130Oq-umrvXME4JhEpO0Wadoki3kNxx=0-YvTR6PtQ@mail.gmail.com/
> >
> > I have some thoughts on how I could fix this, but I need to think
> > about a few cases.

Not sure if this is related.. Some drivers need to be updated from
builtin_platform_driver_probe() to use builtin_platform_driver() when
switching to simple-pm-bus because of deferred probe. See more info
in commit e259c2926c01 ("PCI: pci-dra7xx: Prepare for deferred probe
with module_platform_driver").

Regards,

Tony

  reply	other threads:[~2021-11-16  5:21 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-29  0:07 [PATCH v4 0/2] Fix simple-bus issues with fw_devlink Saravana Kannan
2021-09-29  0:07 ` [PATCH v4 1/2] drivers: bus: simple-pm-bus: Add support for probing simple bus only devices Saravana Kannan
2021-10-05 15:07   ` Geert Uytterhoeven
2021-11-10 12:16   ` Abel Vesa
2021-11-10 20:24     ` Saravana Kannan
2021-11-15 20:17       ` Saravana Kannan
2021-11-16  5:19         ` Tony Lindgren [this message]
2021-11-16 13:59         ` Abel Vesa
2021-11-16 15:11           ` Abel Vesa
2021-11-19 16:16             ` Abel Vesa
2021-11-24  1:07               ` Saravana Kannan
2022-02-01  3:18   ` Kevin Hilman
2022-02-01  5:30     ` Saravana Kannan
2022-02-01 18:36       ` Kevin Hilman
2022-02-02 19:58         ` Kevin Hilman
2021-09-29  0:07 ` [PATCH v4 2/2] drivers: bus: Delete CONFIG_SIMPLE_PM_BUS Saravana Kannan
2021-10-05 15:11   ` Geert Uytterhoeven
2021-10-21 11:21   ` Amit Pundir
2021-10-21 12:37     ` Tony Lindgren
2021-10-21 23:42     ` Saravana Kannan
2021-10-22 16:59       ` Amit Pundir
2021-10-26  0:30         ` Saravana Kannan
2021-10-26 17:49           ` Amit Pundir
2021-09-30  2:50 ` [PATCH v4 0/2] Fix simple-bus issues with fw_devlink Damien Le Moal
2021-10-06  5:29 ` Tony Lindgren

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=YZM/b2/F8xmK43vr@atomide.com \
    --to=tony@atomide.com \
    --cc=abelvesa@kernel.org \
    --cc=catalin.marinas@arm.com \
    --cc=damien.lemoal@wdc.com \
    --cc=geert+renesas@glider.be \
    --cc=gregkh@linuxfoundation.org \
    --cc=kernel-team@android.com \
    --cc=linux-arm-kernel@lists.infradead.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-omap@vger.kernel.org \
    --cc=linux-oxnas@groups.io \
    --cc=linux-renesas-soc@vger.kernel.org \
    --cc=linux-riscv@lists.infradead.org \
    --cc=linux@armlinux.org.uk \
    --cc=magnus.damm@gmail.com \
    --cc=narmstrong@baylibre.com \
    --cc=robh+dt@kernel.org \
    --cc=saravanak@google.com \
    --cc=ulf.hansson@linaro.org \
    --cc=will@kernel.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).