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From:   "Jason A. Donenfeld" <Jason@zx2c4.com>
Date:   Wed, 29 Jun 2022 18:52:08 +0200
Message-ID: <CAHmME9rwKmEQcn84GfTrCPzaK3g6vh6rpQ=YcgyTo_PWpJ5VcA@mail.gmail.com>
Subject: Re: [PATCH] remove CONFIG_ANDROID
To:     Christoph Hellwig <hch@lst.de>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        =?UTF-8?B?QXJ2ZSBIasO4bm5ldsOlZw==?= <arve@android.com>,
        Todd Kjos <tkjos@android.com>,
        Martijn Coenen <maco@android.com>,
        Joel Fernandes <joel@joelfernandes.org>,
        Christian Brauner <brauner@kernel.org>,
        Hridya Valsaraju <hridya@google.com>,
        Suren Baghdasaryan <surenb@google.com>,
        "Theodore Ts'o" <tytso@mit.edu>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>,
        Paolo Abeni <pabeni@redhat.com>, Rob Herring <robh@kernel.org>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Frederic Weisbecker <frederic@kernel.org>,
        Neeraj Upadhyay <quic_neeraju@quicinc.com>,
        Josh Triplett <josh@joshtriplett.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Shuah Khan <shuah@kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
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On Wed, Jun 29, 2022 at 6:45 PM Christoph Hellwig <hch@lst.de> wrote:
>
> On Wed, Jun 29, 2022 at 06:38:09PM +0200, Jason A. Donenfeld wrote:
> > On the technical topic, an Android developer friend following this
> > thread just pointed out to me that Android doesn't use PM_AUTOSLEEP and
> > just has userspace causing suspend frequently. So by his rough
> > estimation your patch actually *will* break Android devices. Zoinks.
> > Maybe he's right, maybe he's not -- I don't know -- but you should
> > probably look into this if you want this patch to land without breakage.
>
> And it will also "break" anyone else doing frequent suspends from
> userspace, as that behavior is still in no way related to
> CONFIG_ANDROID.

I don't know of any actual systems that do this for which
CONFIG_PM_AUTOSLEEP and CONFIG_ANDROID are both disabled. At least
that was what I concluded back in 2017-2018 when I looked at this
last. And so far, no other-handset-users have reported bugs.

But of course I agree that this all could be improved with something
more granular somehow, somewhere. I don't really have any developed
opinions on what that looks like or what form that should take.

However, the thing I do have a strong opinion on is that the change
you're proposing shouldn't break things. And that's what your patch
currently might do (or not!).

In other words, instead of making the current situation worse,
justified by your observation that in theory the current mechanism is
imperfect, please make the situation better. Or conclude that it
doesn't make the situation worse, and put the reason why inside your
commit message, which is the first thing I asked.

Jason