linux-kernel - Re: [PATCH v1] clk: Add devm_clk_{prepare,enable,prepare

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Date:   Mon, 25 Nov 2019 12:55:30 +0000
From:   Russell King - ARM Linux admin <linux@...linux.org.uk>
To:     Marc Gonzalez <marc.w.gonzalez@...e.fr>
Cc:     Stephen Boyd <sboyd@...nel.org>,
        Michael Turquette <mturquette@...libre.com>,
        linux-clk <linux-clk@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v1] clk: Add devm_clk_{prepare,enable,prepare_enable}

On Mon, Nov 25, 2019 at 01:46:51PM +0100, Marc Gonzalez wrote:
> On 15/07/2019 17:34, Marc Gonzalez wrote:
> 
> > Provide devm variants for automatic resource release on device removal.
> > probe() error-handling is simpler, and remove is no longer required.
> > 
> > Signed-off-by: Marc Gonzalez <marc.w.gonzalez@...e.fr>
> > ---
> >  Documentation/driver-model/devres.rst |  3 +++
> >  drivers/clk/clk.c                     | 24 ++++++++++++++++++++++++
> >  include/linux/clk.h                   |  8 ++++++++
> >  3 files changed, 35 insertions(+)
> > 
> > diff --git a/Documentation/driver-model/devres.rst b/Documentation/driver-model/devres.rst
> > index 1b6ced8e4294..9357260576ef 100644
> > --- a/Documentation/driver-model/devres.rst
> > +++ b/Documentation/driver-model/devres.rst
> > @@ -253,6 +253,9 @@ CLOCK
> >    devm_clk_hw_register()
> >    devm_of_clk_add_hw_provider()
> >    devm_clk_hw_register_clkdev()
> > +  devm_clk_prepare()
> > +  devm_clk_enable()
> > +  devm_clk_prepare_enable()
> >  
> >  DMA
> >    dmaenginem_async_device_register()
> > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> > index c0990703ce54..5e85548357c0 100644
> > --- a/drivers/clk/clk.c
> > +++ b/drivers/clk/clk.c
> > @@ -914,6 +914,18 @@ int clk_prepare(struct clk *clk)
> >  }
> >  EXPORT_SYMBOL_GPL(clk_prepare);
> >  
> > +static void unprepare(void *clk)
> > +{
> > +	clk_unprepare(clk);
> > +}
> > +
> > +int devm_clk_prepare(struct device *dev, struct clk *clk)
> > +{
> > +	int rc = clk_prepare(clk);
> > +	return rc ? : devm_add_action_or_reset(dev, unprepare, clk);
> > +}
> > +EXPORT_SYMBOL_GPL(devm_clk_prepare);
> > +
> >  static void clk_core_disable(struct clk_core *core)
> >  {
> >  	lockdep_assert_held(&enable_lock);
> > @@ -1136,6 +1148,18 @@ int clk_enable(struct clk *clk)
> >  }
> >  EXPORT_SYMBOL_GPL(clk_enable);
> >  
> > +static void disable(void *clk)
> > +{
> > +	clk_disable(clk);
> > +}
> > +
> > +int devm_clk_enable(struct device *dev, struct clk *clk)
> > +{
> > +	int rc = clk_enable(clk);
> > +	return rc ? : devm_add_action_or_reset(dev, disable, clk);
> > +}
> > +EXPORT_SYMBOL_GPL(devm_clk_enable);
> > +
> >  static int clk_core_prepare_enable(struct clk_core *core)
> >  {
> >  	int ret;
> > diff --git a/include/linux/clk.h b/include/linux/clk.h
> > index 3c096c7a51dc..d09b5207e3f1 100644
> > --- a/include/linux/clk.h
> > +++ b/include/linux/clk.h
> > @@ -895,6 +895,14 @@ static inline void clk_restore_context(void) {}
> >  
> >  #endif
> >  
> > +int devm_clk_prepare(struct device *dev, struct clk *clk);
> > +int devm_clk_enable(struct device *dev, struct clk *clk);
> > +static inline int devm_clk_prepare_enable(struct device *dev, struct clk *clk)
> > +{
> > +	int rc = devm_clk_prepare(dev, clk);
> > +	return rc ? : devm_clk_enable(dev, clk);
> > +}
> > +
> >  /* clk_prepare_enable helps cases using clk_enable in non-atomic context. */
> >  static inline int clk_prepare_enable(struct clk *clk)
> >  {
> 
> Thoughts? Comments?

It's also worth reading https://lore.kernel.org/patchwork/patch/755667/
and considering whether you really are using the clk_prepare() and
clk_enable() APIs correctly.  Wanting these devm functions suggests
you aren't...

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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