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

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Message-ID: <565991B0.5030909@gmail.com>
Date:	Sat, 28 Nov 2015 12:36:16 +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 23.11.2015 05:59, Jisheng Zhang wrote:
> On Fri, 20 Nov 2015 21:19:46 +0100
> Sebastian Hesselbarth wrote:
>> 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>
>>>>> ---
[...]
>>>>> +			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.
> 
> That's fine.

Jisheng,

I amended your SoC dtsi watchdog patches accordingly. wdt0 is
now always enabled, while the others are disabled.

So, with the changes Patches 1-4 applied to berlin/dt and berlin64/dt
respectively. Patches 5-8 dropped.

>> As soon as the driver issue is resolved, we enable all wdt nodes
>> unconditionally.
> 
> I will submit patch for the wdt driver and hope it will be merged
> in v4.5.

Ok. Feel free to add a patch that removes the status disabled properties
again if berlin[64]/dt has already hit mainline in the meantime.

If not, keep me posted on the DW wdt patch outcome.

Thanks,

Sebastian
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