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From: Stephen Boyd <sboyd@kernel.org>
To: Jerome Brunet <jbrunet@baylibre.com>,
	Michael Turquette <mturquette@baylibre.com>
Cc: Kevin Hilman <khilman@baylibre.com>, linux-clk@vger.kernel.org
Subject: Re: [PATCH RFC 4/5] clk: add placeholder for clock internal data
Date: Thu, 29 Aug 2019 10:17:42 -0700
Message-ID: <20190829171743.577932173E@mail.kernel.org> (raw)
In-Reply-To: <1jy2zcv3nd.fsf@starbuckisacylon.baylibre.com>

Quoting Jerome Brunet (2019-08-29 00:20:38)
> On Wed 28 Aug 2019 at 15:15, Stephen Boyd <sboyd@kernel.org> wrote:
> 
> > Quoting Jerome Brunet (2019-08-28 03:20:11)
> >> Add placeholder in clock core to save per clock data.
> >> Such placeholder could use for clock doing memory allocation in .init().
> >> It may also be useful for the save/restore_context() callbacks.
> >> 
> >> Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
> >> ---
> >>  drivers/clk/clk.c            | 13 +++++++++++++
> >>  include/linux/clk-provider.h |  2 ++
> >>  2 files changed, 15 insertions(+)
> >> 
> >> diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
> >> index c703aa35ca37..aa77a2a98ea4 100644
> >> --- a/drivers/clk/clk.c
> >> +++ b/drivers/clk/clk.c
> >> @@ -83,6 +83,7 @@ struct clk_core {
> >>         struct hlist_node       debug_node;
> >>  #endif
> >>         struct kref             ref;
> >> +       void                    *priv;
> >
> > Why? We have container structures around clk_hw that can be used to
> > store data and clk_ops that should know to deref said clk_hw pointer in
> > some way to access that data.
> 
> This simple addition give a placeholder to each clock instance that is
> hosted under the clock core so we know it can only be accesed from this
> particular instance. Seems like a better fit for runtime data, such as
> saved context.
> 
> It gives a way to avoid mixing the clock description and its runtime
> data. In the end, It would be nice if the clock description part could
> be made const.
> 
> This is a (fairly usual) way to do it 

Maybe you can provide an example or usage? Is that the last patch in
this series? I still don't quite understand why we need this.

I imagine that if you wanted to have a const description part you could
have a container structure around the clk_hw struct

	struct my_clk_foo {
		const struct clk_description *desc;
		<runtime modifiable members>;
		struct clk_hw hw;
	};

Did I miss something?


  reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-08-28 10:20 [PATCH RFC 0/5] clk: let clock claim resources Jerome Brunet
2019-08-28 10:20 ` [PATCH RFC 1/5] clk: actually call the clock init before any other callback of the clock Jerome Brunet
2019-08-28 10:20 ` [PATCH RFC 2/5] clk: let init callback return an error code Jerome Brunet
2019-08-28 10:20 ` [PATCH RFC 3/5] clk: add terminate callback to clk_ops Jerome Brunet
2019-08-28 10:20 ` [PATCH RFC 4/5] clk: add placeholder for clock internal data Jerome Brunet
2019-08-28 22:15   ` Stephen Boyd
2019-08-29  7:20     ` Jerome Brunet
2019-08-29 17:17       ` Stephen Boyd [this message]
2019-08-30 14:06         ` Jerome Brunet
2019-09-04 22:52           ` Stephen Boyd
2019-08-28 10:20 ` [PATCH RFC 5/5] clk: meson: sclk-div: use runtime data Jerome Brunet

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