linux-kernel - Re: [PATCH 1/2] reset: add reset-simple to unify socfpga, stm32, and sunxi

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Date:   Wed, 8 Mar 2017 14:03:32 +0000
From:   Andre Przywara <andre.przywara@....com>
To:     Philipp Zabel <p.zabel@...gutronix.de>,
        Alexandre Torgue <alexandre.torgue@...com>
Cc:     linux-kernel@...r.kernel.org,
        Maxime Coquelin <mcoquelin.stm32@...il.com>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Chen-Yu Tsai <wens@...e.org>
Subject: Re: [PATCH 1/2] reset: add reset-simple to unify socfpga, stm32, and
 sunxi

Hi,

On 08/03/17 12:20, Philipp Zabel wrote:
> On Wed, 2017-03-08 at 12:05 +0100, Alexandre Torgue wrote:
>> Hi Philipp,
>>
>> On 03/08/2017 11:19 AM, Andre Przywara wrote:
>>> Hi,
>>>
>>> On 08/03/17 09:54, Philipp Zabel wrote:
>>>> Reset operations for simple reset controllers with reset lines that can
>>>> be controlled by toggling bits in (mostly) contiguous register ranges
>>>> using read-modify-write cycles under a spinlock. So far this covers the
>>>> socfpga, stm32, and sunxi drivers.
>>>
>>> Wow, that looks nice, thanks for that.
>>>
>>> But can't we go one step further and unify those driver into one file then?
>>> And either have different probe functions to cover the different DT
>>> requirements or to just have one unified probe checking for the super
>>> set of all properties?
>>
>> I agree with Andre. It looks nice and it should be a good thing to have 
>> a common probe inside reset-simple.c
>> Maybe only "nresets" and "inverted"  DT properties are needed.
> 
> Adding DT properties is not an option, as the driver would have to work
> with the existing bindings. We could merge them into one file, with a
> single probe function that configures different parameters depending on
> the of_device_id returned by of_match_device.

Yes, either that or we could just parse all possible properties, as
allowing additional properties on top of the documented binding doc
shouldn't hurt, I think. That's what I mean with super-set. I have to
check if this is acceptable, though.

And I think it would be worthwhile to create a generic binding (or at
least a generic compatible string) on the way, specifying all the
existing properties there, so new drivers could just use that without
having to add their own compatible string to the *driver* (but just to
the binding doc). This would have the advantage of new SoCs possibly
being supported without actual kernel changes.

Cheers,
Andre.