From: "dbasehore ." <dbasehore@chromium.org>
To: sboyd@kernel.org
Cc: linux-kernel <linux-kernel@vger.kernel.org>,
linux-clk@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
linux-rockchip@lists.infradead.org, linux-doc@vger.kernel.org,
"Michael Turquette" <mturquette@baylibre.com>,
"Heiko Stübner" <heiko@sntech.de>,
aisheng.dong@nxp.com, mchehab+samsung@kernel.org, corbet@lwn.net,
"Stephen Boyd" <sboyd@codeaurora.org>,
jbrunet@baylibre.com
Subject: Re: [PATCH 1/6] clk: Remove recursion in clk_core_{prepare,enable}()
Date: Wed, 24 Oct 2018 13:09:07 -0700 [thread overview]
Message-ID: <CAGAzgspGA0CExLBrJvM8E7a1ybp=PRDz6kJ-dKyp0hi9db-19g@mail.gmail.com> (raw)
In-Reply-To: <154038647375.53599.631725372765617195@swboyd.mtv.corp.google.com>
On Wed, Oct 24, 2018 at 6:07 AM Stephen Boyd <sboyd@kernel.org> wrote:
>
> Quoting Derek Basehore (2018-10-23 18:31:27)
> > From: Stephen Boyd <sboyd@codeaurora.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@baylibre.com>
> > Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
> > Signed-off-by: Derek Basehore <dbasehore@chromium.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/
next prev parent reply other threads:[~2018-10-24 20:09 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-24 1:31 [PATCH 0/6] Coordinated Clks Derek Basehore
2018-10-24 1:31 ` [PATCH 1/6] clk: Remove recursion in clk_core_{prepare,enable}() Derek Basehore
2018-10-24 9:51 ` Jerome Brunet
2018-10-24 20:15 ` dbasehore .
2018-10-24 20:23 ` dbasehore .
2018-10-24 20:50 ` dbasehore .
2018-10-25 8:57 ` Jerome Brunet
2018-10-24 20:36 ` dbasehore .
2018-10-25 8:12 ` Jerome Brunet
2018-10-24 13:07 ` Stephen Boyd
2018-10-24 20:09 ` dbasehore . [this message]
2018-10-24 1:31 ` [PATCH 2/6] clk: fix clk_calc_subtree compute duplications Derek Basehore
2018-11-01 2:58 ` dbasehore .
2018-10-24 1:31 ` [PATCH 3/6] clk: change rates via list iteration Derek Basehore
2018-10-26 3:29 ` dbasehore .
2018-10-24 1:31 ` [PATCH 4/6] clk: add pre clk changes support Derek Basehore
2018-10-24 1:31 ` [PATCH 5/6] docs: driver-api: add pre_rate_req to clk documentation Derek Basehore
2018-10-24 1:31 ` [PATCH 6/6] clk: rockchip: use pre_rate_req for cpuclk Derek Basehore
2018-10-24 4:06 ` dbasehore .
2018-12-20 21:15 ` [PATCH 0/6] Coordinated Clks Stephen Boyd
2018-12-20 23:20 ` dbasehore .
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