linux-kernel - Re: [PATCH 2/2] clk: core: link consumer with clock driver

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Message-ID: <20181203231655.4e7dc330@xps13>
Date:   Mon, 3 Dec 2018 23:16:55 +0100
From:   Miquel Raynal <miquel.raynal@...tlin.com>
To:     Stephen Boyd <sboyd@...nel.org>
Cc:     kbuild test robot <lkp@...el.com>, kbuild-all@...org,
        Michael Turquette <mturquette@...libre.com>,
        Russell King <linux@...linux.org.uk>,
        linux-clk@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        Antoine Tenart <antoine.tenart@...tlin.com>,
        Maxime Chevallier <maxime.chevallier@...tlin.com>,
        Gregory Clement <gregory.clement@...tlin.com>,
        Nadav Haklai <nadavh@...vell.com>
Subject: Re: [PATCH 2/2] clk: core: link consumer with clock driver

Hi Stephen,

Stephen Boyd <sboyd@...nel.org> wrote on Mon, 03 Dec 2018 11:20:31
-0800:

> Quoting Miquel Raynal (2018-11-30 02:20:52)
> > Hi Stephen,
> > 
> > Stephen Boyd <sboyd@...nel.org> wrote on Fri, 30 Nov 2018 01:26:20
> > -0800:
> >   
> > > Quoting Miquel Raynal (2018-11-23 01:11:32)  
> > > > Would you agree with me adding dummy functions in the #else section
> > > > like:
> > > > 
> > > > static inline void __clk_device_link(struct device *consumer, struct clk *clk)
> > > > {
> > > >        return;
> > > > }
> > > > 
> > > > static inline void __clk_device_unlink(struct clk *clk)
> > > > {
> > > >        return;
> > > > }
> > > > 
> > > > Do you want me to also declare these functions in the #if section
> > > > (with the external keyword) to balance the above declarations?    
> > > 
> > > Why can't we do the linking in __clk_get() and __clk_put()?
> > >   
> > 
> > Because we need the caller's 'struct device' to make the link and
> > this is not available in __clk_get(). I tried to ad it as parameter but
> > I don't think it is possible to retrieve a 'struct device' from the
> > device name. The functions where this is problematic are:
> > * clk.c:__of_clk_get_from_provider()
> > * clkdev.c:clk_get_sys()
> > 
> > By the way in my new version I called the helpers:
> > * clk_{link,unlink}_hierarchy()
> > * clk_{link,unlink}_consumer()
> > 
> > I will send a new version with these helpers, but if you have anything
> > in mind to help me achieve the above request, I will welcome the idea.
> >   
> 
> We can do the linking in __clk_get() and __clk_put() if we poke into the
> struct clk -> struct clk_core and bury the struct device into each
> clk_core structure.
> 

I meant the consumer device's structure. Yes, from a struct clk, the
first change in patch 1/2 let's us do clk->core->dev to get the clock
device. But for linking I need both the clock device and the consumer
device; and the latter will be missing in __clk_get().


Thanks,
Miquèl