linux-kernel - Re: [PATCH v6 4/5] ARM: DTS: da850: Add cfgchip syscon node

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Date:   Fri, 28 Oct 2016 12:24:06 -0500
From:   David Lechner <david@...hnology.com>
To:     Kevin Hilman <khilman@...libre.com>, Sekhar Nori <nsekhar@...com>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Axel Haslam <ahaslam@...libre.com>,
        Sergei Shtylyov <sergei.shtylyov@...entembedded.com>,
        devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v6 4/5] ARM: DTS: da850: Add cfgchip syscon node

On 10/28/2016 12:08 PM, Kevin Hilman wrote:
> Sekhar Nori <nsekhar@...com> writes:
>
>> On Wednesday 26 October 2016 09:38 PM, David Lechner wrote:
>>> On 10/25/2016 10:06 PM, David Lechner wrote:
>>>> Add a syscon node for the SoC CFGCHIPn registers. This is needed for
>>>> the new usb phy driver.
>>>>
>>>> Signed-off-by: David Lechner <david@...hnology.com>
>>>> ---
>>>>  arch/arm/boot/dts/da850.dtsi | 4 ++++
>>>>  1 file changed, 4 insertions(+)
>>>>
>>>> diff --git a/arch/arm/boot/dts/da850.dtsi b/arch/arm/boot/dts/da850.dtsi
>>>> index f79e1b9..6bbf20d 100644
>>>> --- a/arch/arm/boot/dts/da850.dtsi
>>>> +++ b/arch/arm/boot/dts/da850.dtsi
>>>> @@ -188,6 +188,10 @@
>>>>              };
>>>>
>>>>          };
>>>> +        cfgchip: cfgchip@...7c {
>>>
>>> I wonder if there is a more generic name instead of cfgchip@. Is there a
>>> preferred generic name for syscon nodes?
>>
>> I did not find anything in ePAPR, but chip-controller might be more
>> appropriate.
>>
>>>
>>>> +            compatible = "ti,da830-cfgchip", "syscon";
>>
>> Looks like we need "simple-mfd" too in the compatible list?
>>
>> I think we can also fold patch 5/5 into this patch and add the cfgchip
>> along with USB phy child node included.
>>
>> If you respin the patch, I can drop 4/5 and 5/5 that I have queued and
>> included the updated patch instead.
>
> Sekhar, what's your opinion of having this syscon just for CFGCHIP* vs
> a single syscon for the whole SYSCFG0 region.
>
> The drivers/bus driver from Bartosz is also using SYSCFG0 registers, and
> proposing a sysconf ro this region, but it will need to exclude the
> CFGCHIPn registers if we also have this syscon.

What about the pinmux registers, which are already being used separately 
too?

>
> I tend to think we should just have one for the whole SYSCFG0 which
> this series could use.
>
> Unfortunately, the PHY driver is already merged and it references the
> syscon by compatible.  The PHY driver should probably be fixed to find
> its syscon by phandle, and then maybe we could move to a single syscon
> for SYSCFG0?

I agree that this should be change, but I was thinking we should use 
syscon_node_to_regmap(np->parent) since the phy node should be a child 
of the syscon node.

>
> Let us know your preference, I don't have a very strong feeling either
> way, but since we're already part way down the path of the CFGCHIP
> syscon, we should keep it and later migrate it to one for all of
> SYSCFG0.
>
> Kevin
>