Date:	Fri, 08 Jul 2016 09:08:24 -0700
From:	Michael Turquette <mturquette@...libre.com>
To:	Gabriel Fernandez <gabriel.fernandez@...com>,
	"Rob Herring" <robh@...nel.org>,
	"Gabriel Fernandez" <gabriel.fernandez@...aro.org>
Cc:	"Mark Rutland" <mark.rutland@....com>,
	"Ian Campbell" <ijc+devicetree@...lion.org.uk>,
	"Kumar Gala" <galak@...eaurora.org>,
	"Srinivas Kandagatla" <srinivas.kandagatla@...il.com>,
	"Maxime Coquelin" <maxime.coquelin@...com>,
	"Patrice Chotard" <patrice.chotard@...com>,
	"Russell King" <linux@...linux.org.uk>,
	"Stephen Boyd" <sboyd@...eaurora.org>,
	"Olivier Bideau" <olivier.bideau@...com>,
	"Geert Uytterhoeven" <geert+renesas@...der.be>,
	"Sebastian Hesselbarth" <sebastian.hesselbarth@...il.com>,
	"Andrzej Hajda" <a.hajda@...sung.com>,
	"Pankaj Dev" <pankaj.dev@...com>,
	"Dinh Nguyen" <dinguyen@...nsource.altera.com>,
	"Arnd Bergmann" <arnd@...db.de>,
	"Thierry Reding" <treding@...dia.com>, devicetree@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	kernel@...inux.com, linux-clk@...r.kernel.org,
	"Lee Jones" <lee.jones@...aro.org>,
	"Peter Griffin" <peter.griffin@...aro.org>,
	arnaud.pouliquen@...com, benjamin.gaignard@...com,
	vincent.abriou@...com
Subject: Re: [RESEND PATCH v2 02/13] drivers: clk: st: Simplify clock binding of
 STiH4xx platforms

Quoting Gabriel Fernandez (2016-07-08 02:12:35)
> Hi Mike,
> 
> On 07/08/2016 03:43 AM, Michael Turquette wrote:
> > Quoting Rob Herring (2016-06-19 08:04:58)
> >> On Thu, Jun 16, 2016 at 11:20:22AM +0200, Gabriel Fernandez wrote:
> >>> This patch reworks the clock binding to avoid too much detail in DT.
> >>> Now we have only compatible string per type of clock
> >>> (remark from Rob https://lkml.org/lkml/2016/5/25/492)
> >>>
> >> I have no idea what the clock trees and clock controller in these chips
> >> look like, so it's hard to say if the changes here are good. It still
> >> looks like things are somewhat fine grained clocks in DT. I'll leave
> >> it up to the platform maintainers to decide...
> > Is this series breaking ABI? If yes, why not do what Maxime did for the
> > Allwinner/sunxi clocks and just fully convert over to a
> > one-node-per-clock-controller binding? This one-node-per-clock stuff is
> > pretty unfortunate, and if we're deprecating platforms (patch #1) then
> > now might be a good time to re-evaluate the whole thing.
> 
> The goal of my patchset was to be aligned with DRM / KMS development and 
> to offer
> the possibility to make a correct video playback on STiH407/STiH410 
> platform.
> Our milestone is the 4.8 for that.
> 
> Currently people need these patches to work.
> I'm not sure it's a good time to re-evaluate the whole thing.
> 
> Is it possible to re-evaluate later ?

Are you OK to break ABI later? Or at a minimum, deprecate the current
binding (maintain it forever for legacy platforms) and create a new
clock controller binding description that supersedes the legacy binding
for all new platforms?

If the answer to either question is "yes", then I'm OK to put it aside
for now. But if the answer to both is "no", and this patch series is
breaking ABI, then we really should fix it now.

Regards,
Mike

> 
> Best regards,
> Gabriel
> 
> > Regards,
> > Mike
> >
> >>   
> >>> Signed-off-by: Gabriel Fernandez <gabriel.fernandez@...aro.org>
> >>> ---
> >>>   .../devicetree/bindings/clock/st/st,clkgen-mux.txt |  2 +-
> >>>   .../devicetree/bindings/clock/st/st,clkgen-pll.txt | 11 ++--
> >>>   .../devicetree/bindings/clock/st/st,clkgen.txt     |  2 +-
> >>>   .../devicetree/bindings/clock/st/st,quadfs.txt     |  6 +--
> >>>   drivers/clk/st/clkgen-fsyn.c                       | 41 ++++++--------
> >>>   drivers/clk/st/clkgen-mux.c                        | 28 ++++------
> >>>   drivers/clk/st/clkgen-pll.c                        | 62 ++++++++++------------
> >>>   7 files changed, 65 insertions(+), 87 deletions(-)
> >>>
> >>> diff --git a/Documentation/devicetree/bindings/clock/st/st,clkgen-mux.txt b/Documentation/devicetree/bindings/clock/st/st,clkgen-mux.txt
> >>> index 4d277d6..9a46cb1d7 100644
> >>> --- a/Documentation/devicetree/bindings/clock/st/st,clkgen-mux.txt
> >>> +++ b/Documentation/devicetree/bindings/clock/st/st,clkgen-mux.txt
> >>> @@ -10,7 +10,7 @@ This binding uses the common clock binding[1].
> >>>   Required properties:
> >>>   
> >>>   - compatible : shall be:
> >>> -     "st,stih407-clkgen-a9-mux",     "st,clkgen-mux"
> >>> +     "st,stih407-clkgen-a9-mux"
> >>>   
> >>>   - #clock-cells : from common clock binding; shall be set to 0.
> >>>   
> >>> diff --git a/Documentation/devicetree/bindings/clock/st/st,clkgen-pll.txt b/Documentation/devicetree/bindings/clock/st/st,clkgen-pll.txt
> >>> index c9fd674..be0b043 100644
> >>> --- a/Documentation/devicetree/bindings/clock/st/st,clkgen-pll.txt
> >>> +++ b/Documentation/devicetree/bindings/clock/st/st,clkgen-pll.txt
> >>> @@ -9,11 +9,10 @@ Base address is located to the parent node. See clock binding[2]
> >>>   Required properties:
> >>>   
> >>>   - compatible : shall be:
> >>> -     "st,stih407-plls-c32-a0",       "st,clkgen-plls-c32"
> >>> -     "st,stih407-plls-c32-a9",       "st,clkgen-plls-c32"
> >>> -     "sst,plls-c32-cx_0",            "st,clkgen-plls-c32"
> >>> -     "sst,plls-c32-cx_1",            "st,clkgen-plls-c32"
> >>> -     "st,stih418-plls-c28-a9",       "st,clkgen-plls-c32"
> >>> +     "st,clkgen-pll0"
> >>> +     "st,clkgen-pll0"
> >> Repeated. Supposed to be 0 and 1? This seems a bit generic, too.
> >>
> >>> +     "st,stih407-clkgen-plla9"
> >>> +     "st,stih418-clkgen-plla9"
> 

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