linux-kernel - Re: Question on pre running clocks

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Date:   Mon, 23 Oct 2023 19:42:01 -0700
From:   Stephen Boyd <sboyd@...nel.org>
To:     Arun KS <arunks.linux@...il.com>, linux-clk@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     mturquette@...libre.com, Arun KS <getarunks@...il.com>
Subject: Re: Question on pre running clocks

Quoting Arun KS (2023-10-20 00:09:05)
> + linux-clk
> 
> On Fri, Oct 20, 2023 at 12:37 PM Arun KS <arunks.linux@...il.com> wrote:
> >
> > Hello,
> >
> > Lets say there is a clock which is enabled by bootloaders and is pre
> > running as linux boots.
> > Is it mandatory for the client drivers to call clk_prepare_enable() on
> > them to initialise the enable_count to 1?

Yes.

> >
> > Or is there a way we can specify to the kernel that this clock is
> > already enabled by bootloader and initialise the enable_count for this
> > clock to 1.

No there isn't.

> >
> > Because otherwise, clk_disable() prints a WARN() if a client driver
> > uses clock handle where clk_prepare_enable() is not called.
> >
> > I grep through the code, but could find any details. Appreciate any pointers.
> >
> > Regards,
> > Arun