linux-kernel - Re: [RFC v1 0/4] Simplify regulator supply resolution code by offloading to driver core

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Message-ID: <CAGETcx8iFzHVpwvZ8y+Asq1b6rtfc_-5-FYsvZKWhVPvFm5UsA@mail.gmail.com>
Date:   Sat, 18 Feb 2023 00:36:31 -0800
From:   Saravana Kannan <saravanak@...gle.com>
To:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Geert Uytterhoeven <geert@...ux-m68k.org>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Bjorn Andersson <andersson@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Tony Lindgren <tony@...mide.com>,
        Doug Anderson <dianders@...omium.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Luca Weiss <luca.weiss@...rphone.com>, kernel-team@...roid.com,
        linux-kernel@...r.kernel.org,
        Christian Kohlschütter 
        <christian@...lschutter.com>
Subject: Re: [RFC v1 0/4] Simplify regulator supply resolution code by
 offloading to driver core

On Sat, Feb 18, 2023 at 12:32 AM Saravana Kannan <saravanak@...gle.com> wrote:
>
> Hi Mark/Liam,
>
> This series is just an RFC to see if you agree with where this is going.
> Please point out bugs, but don't bother with a proper code review.
>
> The high level idea is to not reimplement what driver core can already
> handle for us and use it to do some of the work. Instead of trying to
> resolve supplies from all different code paths and bits and pieces of
> the tree, we just build it from the root to the leaves by using deferred
> probing to sequence things in the right order.
>
> The last patch is the main one. Rest of them are just setting up for it.
>
> I believe there's room for further simplification but this is what I
> could whip up as a quick first draft that shows the high level idea.
> I'll probably need some help with getting a better understanding of why
> things are done in a specific order in regulator_register() before I
> could attempt simplifying things further.
>
> Ideally, regulator_register() would just have DT parsing, init data
> struct sanity checks and adding the regulator device and then we move
> everything else to into the probe function that's guaranteed to run only
> after the supply has been resolved/ready to resolve.
>
> fw_devlink/device links should further optimize the flow and also allow
> us to simplify some of the guarantees and address some of the existing
> FIXMEs. But this patch series is NOT dependent on fw_devlink or device
> links.
>
> Any thoughts on where this is going?
>
> I've tested this on one hardware I have and it works and nothing is
> broken. But the regulator tree in my hardware isn't that complicated or
> deep. The regulators are also added mostly in the right order (due to
> existing fw_devlink). So if you agree with the idea, the next step is to
> ask people to give it a test.
>
> Also, it's based on driver-core-next since that's what I had synced up
> and had a working baseline. I'll rebase it on the regulator tree when I
> go from RFC -> PATCH.
>
> Thanks,
> Saravana
>
> Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
> Cc: Geert Uytterhoeven <geert@...ux-m68k.org>
> Cc: Marek Szyprowski <m.szyprowski@...sung.com>
> Cc: Bjorn Andersson <andersson@...nel.org>
> Cc: Sudeep Holla <sudeep.holla@....com>
> Cc: Tony Lindgren <tony@...mide.com>
> Cc: Doug Anderson <dianders@...omium.org>
> Cc: Guenter Roeck <linux@...ck-us.net>
> Cc: Luca Weiss <luca.weiss@...rphone.com>

Christian, I was meaning to add you but I forgot. I'll add you to
future versions.

-Saravana

>
> Saravana Kannan (4):
>   regulator: core: Add regulator devices to bus instead of class
>   regulator: core: Add sysfs class backward compatibility
>   regulator: core: Probe regulator devices
>   regulator: core: Move regulator supply resolving to the probe function
>
>  drivers/regulator/core.c         | 102 +++++++++++++++++++------------
>  drivers/regulator/internal.h     |   2 +-
>  drivers/regulator/of_regulator.c |   2 +-
>  3 files changed, 64 insertions(+), 42 deletions(-)
>
> --
> 2.39.2.637.g21b0678d19-goog
>