linux-kernel - Re: [PATCH] clk: Warn about critical clks that fail to enable

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Message-ID: <20191230184615.GA25973@roeck-us.net>
Date:   Mon, 30 Dec 2019 10:46:15 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     Michael Turquette <mturquette@...libre.com>,
        linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org,
        Jerome Brunet <jbrunet@...libre.com>
Subject: Re: [PATCH] clk: Warn about critical clks that fail to enable

On Mon, Dec 30, 2019 at 09:55:17AM -0800, Stephen Boyd wrote:
> Quoting Stephen Boyd (2019-12-26 14:13:54)
> > If we don't warn here users of the CLK_IS_CRITICAL flag may not know
> > that their clk isn't actually enabled because it silently fails to
> > enable. Let's drop a big WARN_ON in that case so developers find these
> > problems faster.
> > 
> > Suggested-by: Jerome Brunet <jbrunet@...libre.com>
> > Cc: Guenter Roeck <linux@...ck-us.net>
> > Signed-off-by: Stephen Boyd <sboyd@...nel.org>
> > ---
> > 
> > I suspect that this may start warning for other users. Let's see
> > and revert in case it doesn't work.
> > 
> >  drivers/clk/clk.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> > index 772258de2d1f..6a9a66dfdeaa 100644
> > --- a/drivers/clk/clk.c
> > +++ b/drivers/clk/clk.c
> > @@ -3427,13 +3427,13 @@ static int __clk_core_init(struct clk_core *core)
> >                 unsigned long flags;
> >  
> >                 ret = clk_core_prepare(core);
> > -               if (ret)
> > +               if (WARN_ON(ret))
> 
> We should probably just print the clk name that failed to be critically
> enabled with a pr_warn(). The traceback pointing to this location will
> be really hard to understand otherwise.
> 
Agreed.

Guenter

> >                         goto out;
> >  
> >                 flags = clk_enable_lock();
> >                 ret = clk_core_enable(core);
> >                 clk_enable_unlock(flags);
> > -               if (ret) {
> > +               if (WARN_ON(ret)) {
> >                         clk_core_unprepare(core);
> >                         goto out;
> >                 }
> > 
> > base-commit: 12ead77432f2ce32dea797742316d15c5800cb32
> > -- 
> > Sent by a computer, using git, on the internet
> >