linux-kernel - Re: [PATCH 4/4] clk: mvebu: Expand mv98dx3236-core-clock support

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Date:   Tue, 7 Feb 2017 03:07:37 +0000
From:   Chris Packham <Chris.Packham@...iedtelesis.co.nz>
To:     Stephen Boyd <sboyd@...eaurora.org>
CC:     "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-clk@...r.kernel.org" <linux-clk@...r.kernel.org>,
        Michael Turquette <mturquette@...libre.com>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Jason Cooper <jason@...edaemon.net>,
        Andrew Lunn <andrew@...n.ch>,
        "Gregory Clement" <gregory.clement@...e-electrons.com>,
        Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>,
        Russell King <linux@...linux.org.uk>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/4] clk: mvebu: Expand mv98dx3236-core-clock support

On 07/02/17 14:25, Chris Packham wrote:
> On 07/02/17 14:13, Chris Packham wrote:
>> On 07/02/17 14:03, Stephen Boyd wrote:
>>> On 02/06, Chris Packham wrote:
>>>> On 07/02/17 12:14, Stephen Boyd wrote:
>>>>> On 02/03, Chris Packham wrote:
>>>>>> The initial implementation in commit e120c17a70e5 ("clk: mvebu: support
>>>>>> for 98DX3236 SoC") hardcoded a fixed value for the main PLL frequency.
>>>>>> Port code from the Marvell supplied Linux kernel to support different
>>>>>> PLL frequencies and provide clock gating support.
>>>>>>
>>>>>> Signed-off-by: Chris Packham <chris.packham@...iedtelesis.co.nz>
>>>>>> ---
>>>>>>  .../devicetree/bindings/clock/mvebu-core-clock.txt |   7 +
>>>>>>  .../bindings/clock/mvebu-gated-clock.txt           |  11 ++
>>>>>>  arch/arm/boot/dts/armada-xp-98dx3236.dtsi          |  14 +-
>>>>>>  drivers/clk/mvebu/Makefile                         |   2 +-
>>>>>>  drivers/clk/mvebu/armada-xp.c                      |  13 --
>>>>>>  drivers/clk/mvebu/mv98dx3236.c                     | 144 +++++++++++++++++++++
>>>>>
>>>>> This mixes dts and clk driver changes. Any chance it can be split
>>>>> up and just have the clk part go through clk tree? Otherwise, I
>>>>> can ack this if you want to take it all through arm-soc?
>>>>
>>>> I'm happy to split it if it will make life easier.
>>>>
>>>
>>> Well do things keep booting if the clk driver parts merge without
>>> the associated dts changes? It's nice to maintain backwards
>>> compatibility even for a short time to make the merge path
>>> easier.
>>>
>>
>> Unfortunately not. I could put the clk changes first (then I'd just have
>> checkpatch.pl complaining about new compatible strings). But if the clk
>> patches don't land before the dts changes the boards won't boot. However
>> that affects 1 person that we know of (me).
>>
>
> Actually I wonder if I can try a bit harder to keep a system booting.
> The following might work
> 1) add the compatible strings to the existing armada clock drivers.
> 2) update the dts to use the new compatible strings.
> 3) add the new driver and remove the compatible strings from the armada
> drivers.
>
> #1 would still upset checkpatch.pl because the documentation would only
> arrive in #2.

Actually upon testing #1 is unnecessary. I lose some of the gated clocks 
but nothing that prevents booting.