linux-kernel - Re: [PATCH RESEND 1/8] arm: dts: berlin2q: add watchdog nodes

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Message-ID: <564F8062.8070609@gmail.com>
Date:	Fri, 20 Nov 2015 21:19:46 +0100
From:	Sebastian Hesselbarth <sebastian.hesselbarth@...il.com>
To:	Jisheng Zhang <jszhang@...vell.com>
Cc:	robh+dt@...nel.org, pawel.moll@....com, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk, galak@...eaurora.org,
	linux@....linux.org.uk, catalin.marinas@....com,
	will.deacon@....com, linux-arm-kernel@...ts.infradead.org,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RESEND 1/8] arm: dts: berlin2q: add watchdog nodes

On 20.11.2015 04:34, Jisheng Zhang wrote:
> On Thu, 19 Nov 2015 21:47:05 +0100
> Sebastian Hesselbarth wrote:
>> On 16.11.2015 12:09, Jisheng Zhang wrote:
>>> The Marvell Berlin BG2Q has 3 watchdogs which are compatible with the
>>> snps,dw-wdt driver sit in the sysmgr domain. This patch adds the
>>> corresponding device tree nodes.
>>>
>>> Signed-off-by: Jisheng Zhang <jszhang@...vell.com>
>>> ---
>>>  arch/arm/boot/dts/berlin2q.dtsi | 24 ++++++++++++++++++++++++
>>>  1 file changed, 24 insertions(+)
>>>
>>> diff --git a/arch/arm/boot/dts/berlin2q.dtsi b/arch/arm/boot/dts/berlin2q.dtsi
>>> index a3ecde5..fac4315 100644
>>> --- a/arch/arm/boot/dts/berlin2q.dtsi
>>> +++ b/arch/arm/boot/dts/berlin2q.dtsi
>>> @@ -483,6 +483,30 @@
>>>  			ranges = <0 0xfc0000 0x10000>;
>>>  			interrupt-parent = <&sic>;
>>>  
>>> +			wdt0: watchdog@...0 {
>>> +				compatible = "snps,dw-wdt";
>>> +				reg = <0x1000 0x100>;
>>> +				clocks = <&refclk>;
>>> +				interrupts = <0>;
>>> +				status = "disabled";  
>>
>> as the watchdogs are internal and cannot be clock gated
>> at all, how about we remove the status = "disabled" and
>> make them always available?
> 
> there are two issues here:
> 
> 1. the dw-wdt can't support multiple variants now. I have rewrite the driver
> with watchdog core supplied framework, but the patch isn't sent out and
> may be need time to clean up and review.

Ok.

> 2. not all dw-wdt devices are available and functional. This depends on
> board design and configuration.

I understand that "board design and configuration" may hinder the wdt
to issue a hard reset. But all others are able to issue a soft reset
or just an interrupt, right?

So, I still don't see why we should disable wdt nodes by default
except for the driver issue above.

> So IMHO status=disabled and patch5-8 is necessary, what do you think?

No. I'd agree to enable wdt0 by default and leave wdt[1,2] disabled
because of the driver issue. Patches 5-8 only enable wdt0 anyway.

As soon as the driver issue is resolved, we enable all wdt nodes
unconditionally.

Sebastian

>> I have applied patches 1-4 with the status property removed.
>> This also renders patches 5-8 useless.
>>
>> So, for now tentatively
>>
>> Appled to berlin/dt and berlin64/dt respectivly
>>
>> with status property removed.
>>
>> Sebastian
>>
> 

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