linux-kernel - Re: [PATCH 1/6] clk: Remove recursion in clk_core

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Message-ID: <CAGAzgspGA0CExLBrJvM8E7a1ybp=PRDz6kJ-dKyp0hi9db-19g@mail.gmail.com>
Date:   Wed, 24 Oct 2018 13:09:07 -0700
From:   "dbasehore ." <dbasehore@...omium.org>
To:     sboyd@...nel.org
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, linux-doc@...r.kernel.org,
        Michael Turquette <mturquette@...libre.com>,
        Heiko Stübner <heiko@...ech.de>,
        aisheng.dong@....com, mchehab+samsung@...nel.org, corbet@....net,
        Stephen Boyd <sboyd@...eaurora.org>, jbrunet@...libre.com
Subject: Re: [PATCH 1/6] clk: Remove recursion in clk_core_{prepare,enable}()

On Wed, Oct 24, 2018 at 6:07 AM Stephen Boyd <sboyd@...nel.org> wrote:
>
> Quoting Derek Basehore (2018-10-23 18:31:27)
> > From: Stephen Boyd <sboyd@...eaurora.org>
> >
> > Enabling and preparing clocks can be written quite naturally with
> > recursion. We start at some point in the tree and recurse up the
> > tree to find the oldest parent clk that needs to be enabled or
> > prepared. Then we enable/prepare and return to the caller, going
> > back to the clk we started at and enabling/preparing along the
> > way.
> >
> > The problem is recursion isn't great for kernel code where we
> > have a limited stack size. Furthermore, we may be calling this
> > code inside clk_set_rate() which also has recursion in it, so
> > we're really not looking good if we encounter a tall clk tree.
> >
> > Let's create a stack instead by looping over the parent chain and
> > collecting clks of interest. Then the enable/prepare becomes as
> > simple as iterating over that list and calling enable.
> >
> > Cc: Jerome Brunet <jbrunet@...libre.com>
> > Signed-off-by: Stephen Boyd <sboyd@...eaurora.org>
> > Signed-off-by: Derek Basehore <dbasehore@...omium.org>
>
> Did you change anything substantially? Or is it just a resend of my
> patch from a while ago? If you can add a link to the original and also
> describe what changed in a maintainer tag it would be much easier for me
> to compare.
>

It should just be your patch with the compilation warning fixed.

This is picked up from https://lore.kernel.org/patchwork/patch/814369/