RE: [PATCH v3 1/2] clk: Provide managed helper to get and enable bulk clocks

[Shradha Todi]

> -----Original Message-----
> From: Manivannan Sadhasivam <manivannan.sadhasivam@xxxxxxxxxx>
> Sent: 20 January 2024 20:33
> To: Shradha Todi <shradha.t@xxxxxxxxxxx>
> Cc: linux-clk@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-
> pci@xxxxxxxxxxxxxxx; linux-arm-kernel@xxxxxxxxxxxxxxxxxxx; linux-samsung-
> soc@xxxxxxxxxxxxxxx; mturquette@xxxxxxxxxxxx; sboyd@xxxxxxxxxx;
> jingoohan1@xxxxxxxxx; lpieralisi@xxxxxxxxxx; kw@xxxxxxxxx; robh@xxxxxxxxxx;
> bhelgaas@xxxxxxxxxx; krzysztof.kozlowski@xxxxxxxxxx;
> alim.akhtar@xxxxxxxxxxx; linux@xxxxxxxxxxxxxxx;
> m.szyprowski@xxxxxxxxxxx
> Subject: Re: [PATCH v3 1/2] clk: Provide managed helper to get and enable bulk
> clocks
> 
> On Wed, Jan 10, 2024 at 04:31:14PM +0530, Shradha Todi wrote:
> > Provide a managed devm_clk_bulk* wrapper to get and enable all bulk
> > clocks in order to simplify drivers that keeps all clocks enabled for
> > the time of driver operation.
> >
> > Suggested-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>
> > Signed-off-by: Shradha Todi <shradha.t@xxxxxxxxxxx>
> > ---
> >  drivers/clk/clk-devres.c | 41
> ++++++++++++++++++++++++++++++++++++++++
> >  include/linux/clk.h      | 25 ++++++++++++++++++++++++
> >  2 files changed, 66 insertions(+)
> >
> > diff --git a/drivers/clk/clk-devres.c b/drivers/clk/clk-devres.c index
> > 4fb4fd4b06bd..05b0ff4bc1d4 100644
> > --- a/drivers/clk/clk-devres.c
> > +++ b/drivers/clk/clk-devres.c
> > @@ -102,6 +102,7 @@
> EXPORT_SYMBOL_GPL(devm_clk_get_optional_enabled);
> >  struct clk_bulk_devres {
> >  	struct clk_bulk_data *clks;
> >  	int num_clks;
> > +	void (*exit)(int num_clks, const struct clk_bulk_data *clks);
> >  };
> >
> >  static void devm_clk_bulk_release(struct device *dev, void *res) @@
> > -182,6 +183,46 @@ int __must_check devm_clk_bulk_get_all(struct device
> > *dev,  }  EXPORT_SYMBOL_GPL(devm_clk_bulk_get_all);
> >
> > +static void devm_clk_bulk_release_all_enabled(struct device *dev,
> > +void *res) {
> > +	struct clk_bulk_devres *devres = res;
> > +
> > +	if (devres->exit)
> > +		devres->exit(devres->num_clks, devres->clks);
> > +
> > +	clk_bulk_put_all(devres->num_clks, devres->clks); }
> > +
> > +int __must_check devm_clk_bulk_get_all_enabled(struct device *dev,
> > +				  struct clk_bulk_data **clks, int *num_clks)
> 
> What is the user supposed to do with "num_clks" when you are already handling
> the enable part?
> 

Since the initial clk_bulk_get_all was returning the num_clks value, the thought was to maintain this
as the user might want to have a check in their driver whether x number of clocks were successfully
retrieved and enabled.

> > +{
> > +	struct clk_bulk_devres *devres;
> > +	int ret;
> > +
> > +	devres = devres_alloc(devm_clk_bulk_release_all_enabled,
> > +			      sizeof(*devres), GFP_KERNEL);
> > +	if (!devres)
> > +		return -ENOMEM;
> > +
> > +	ret = clk_bulk_get_all(dev, &devres->clks);
> > +	if (ret > 0) {
> > +		*clks = devres->clks;
> > +		devres->num_clks = ret;
> > +		*num_clks = ret;
> > +		devres_add(dev, devres);
> 
> If you move the statements inside this condition to the end of this function, you
> could get rid of the exit() callback and directly use
> clk_bulk_disable_unprepare() in devm_clk_bulk_release_all_enabled().
> 

Okay! I will change this in the next patchset as suggested

> > +	} else {
> > +		devres_free(devres);
> > +		return ret;
> > +	}
> > +
> > +	ret = clk_bulk_prepare_enable(devres->num_clks, *clks);
> > +	if (!ret)
> > +		devres->exit = clk_bulk_disable_unprepare;
> 
> Here you can just do clk_bulk_put_all() and devres_free() directly because you
> know that the driver won't proceed after this error.
> 
> - Mani
> 

Thanks for the review, Mani. Will change this as suggested!

> > +
> > +	return ret;
> > +}
> > +EXPORT_SYMBOL_GPL(devm_clk_bulk_get_all_enabled);
> > +
> >  static int devm_clk_match(struct device *dev, void *res, void *data)
> > {
> >  	struct clk **c = res;
> > diff --git a/include/linux/clk.h b/include/linux/clk.h index
> > 1ef013324237..bf3e9bee5754 100644
> > --- a/include/linux/clk.h
> > +++ b/include/linux/clk.h
> > @@ -438,6 +438,24 @@ int __must_check
> > devm_clk_bulk_get_optional(struct device *dev, int num_clks,  int
> __must_check devm_clk_bulk_get_all(struct device *dev,
> >  				       struct clk_bulk_data **clks);
> >
> > +/**
> > + * devm_clk_bulk_get_all_enabled - managed get multiple clk consumers and
> > + *					enable all clk
> > + * @dev: device for clock "consumer"
> > + * @clks: pointer to the clk_bulk_data table of consumer
> > + * @num_clks: out parameter to store the number of clk_bulk_data
> > + *
> > + * Returns success (0) or negative errno.
> > + *
> > + * This helper function allows drivers to get several clk
> > + * consumers and enable all of them in one operation with management.
> > + * The clks will automatically be disabled and freed when the device
> > + * is unbound.
> > + */
> > +
> > +int __must_check devm_clk_bulk_get_all_enabled(struct device *dev,
> > +				struct clk_bulk_data **clks, int *num_clks);
> > +
> >  /**
> >   * devm_clk_get - lookup and obtain a managed reference to a clock producer.
> >   * @dev: device for clock "consumer"
> > @@ -960,6 +978,13 @@ static inline int __must_check
> devm_clk_bulk_get_all(struct device *dev,
> >  	return 0;
> >  }
> >
> > +static inline int __must_check devm_clk_bulk_get_all_enabled(struct device
> *dev,
> > +				struct clk_bulk_data **clks, int *num_clks) {
> > +
> > +	return 0;
> > +}
> > +
> >  static inline struct clk *devm_get_clk_from_child(struct device *dev,
> >  				struct device_node *np, const char *con_id)  {
> > --
> > 2.17.1
> >
> 
> --
> மணிவண்ணன் சதாசிவம்