Re: [Resend Patch v6] driver/clk/clk-si5338: Add common clock framework driver for si5338

[Stephen Boyd <sboyd@codeaurora.org>]

On 10/16, York Sun wrote:
> 
> 
> On 10/16/2015 02:31 PM, Stephen Boyd wrote:
> > On 10/16, York Sun wrote:
> >>
> >>
> >> On 10/09/2015 05:09 PM, Stephen Boyd wrote:
> >>> On 10/09, York Sun wrote:
> >>>> +/*
> >>>> + * To support multiple si5338 chips, we cannot use devm_clk_get because
> >>>> + * each chip has its own clock sources. If device tree is not used,
> >>>> + * platform driver should provide these clocks. Let the clocks be freed
> >>>> + * automatically when device is unbound. We implement our own devm_of_clk_get.
> >>>> + */
> >>>> +static void devm_of_clk_release(struct device *dev, void *res)
> >>>> +{
> >>>> +	clk_put(*(struct clk **)res);
> >>>> +}
> >>>> +
> >>>> +static struct clk *devm_of_clk_get(struct device *dev, struct device_node *np,
> >>>
> >>> What is this? I don't get it at all.
> >>
> >> Maybe you can help me on this.
> >> We have two ways to get parent clock. One is from device tree, the other is from
> >> platform data. When the clock is from platform data, the consumer gets the clock
> >> and passes it. The clock will be put by the consumer as well. When the parent
> >> clock comes from device tree, what I am trying to do is to call of_clk_get(),
> >> without worrying about to call clk_put() later when the driver is removed, so I
> >> don't have to know where the parent clock data came from.
> >>
> > 
> > This driver should always use clk_get() then. If the mode is
> > device tree, clk_get() will lookup the clock in DT and get it
> > from there. If the mode is platform data, then we'll fallback to
> > the clkdev method of clk_get(), which will look for a clk_lookup
> > created for the device calling clk_get() + the connection id that
> > was provided by the lookup creator. This driver should always
> > call clk_put() on the clock when it's done with it, regardless of
> > DT vs. platform data.
> > 
> 
> For the platform data mode, I think it is up to the consumer to get and put the
> parent clocks. The current code is to pass (struct clk *) pointers as parent
> clocks. Are you suggesting to pass the name of parent clocks?
> 

I'm suggesting to register clocks with clkdev using a device name
that matches the consumer. The consumer (this driver?) will
simply call clk_get() and clk_put() then, nothing else is needed.
I'm not suggesting to pass the names of the parent clocks. It
sounds like those are inputs to this device, so we should be
calling clk_get() with a device and a connection id to get the
clock.

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