linux-kernel - Re: [PATCH 5/5] clk: Get runtime PM before walking tree for clk

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Date: Mon, 25 Mar 2024 10:09:15 -0700
From: Stephen Boyd <sboyd@...nel.org>
To: Doug Anderson <dianders@...omium.org>
Cc: Michael Turquette <mturquette@...libre.com>, linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org, patches@...ts.linux.dev, linux-arm-msm@...r.kernel.org, Taniya Das <quic_tdas@...cinc.com>
Subject: Re: [PATCH 5/5] clk: Get runtime PM before walking tree for clk_summary

Quoting Doug Anderson (2024-03-25 09:19:51)
> Hi,
> 
> On Sun, Mar 24, 2024 at 10:44 PM Stephen Boyd <sboyd@...nel.org> wrote:
> >
> > Similar to the previous commit, we should make sure that all devices are
> > runtime resumed before printing the clk_summary through debugfs. Failure
> > to do so would result in a deadlock if the thread is resuming a device
> > to print clk state and that device is also runtime resuming in another
> > thread, e.g the screen is turning on and the display driver is starting
> > up.
> >
> > Fixes: 1bb294a7981c ("clk: Enable/Disable runtime PM for clk_summary")
> > Cc: Taniya Das <quic_tdas@...cinc.com>
> > Cc: Douglas Anderson <dianders@...omium.org>
> > Signed-off-by: Stephen Boyd <sboyd@...nel.org>
> > ---
> >  drivers/clk/clk.c | 6 +++++-
> >  1 file changed, 5 insertions(+), 1 deletion(-)
> 
> Shouldn't this also squash in a revert of commit 1bb294a7981c ("clk:
> Enable/Disable runtime PM for clk_summary")? As it is,
> clk_summary_show_subtree() is left with an extra/unnecessary
> clk_pm_runtime_get() / clk_pm_runtime_put(), right?

Sure, it is superfluous now. I suppose it means we can remove
clk_pm_runtime_get()/put() calls in
clk_{disable,unprepare}_unused_subtree() as well.

> 
> Other than that, this looks good to me:
> 
> Reviewed-by: Douglas Anderson <dianders@...omium.org>