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Subject: Re: [PATCH net-next 1/3] dt-bindings: net: fsl, fec: add "fsl,
 wakeup-irq" property
To:     Joakim Zhang <qiangqing.zhang@nxp.com>,
        "davem@davemloft.net" <davem@davemloft.net>,
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From:   Florian Fainelli <f.fainelli@gmail.com>
Message-ID: <498f3cee-8f37-2ab1-93c4-5472572ecc37@gmail.com>
Date:   Mon, 9 Aug 2021 11:39:40 -0700
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On 8/8/2021 10:08 PM, Joakim Zhang wrote:
> 
> Hi Florian,
> 
>> -----Original Message-----
>> From: Florian Fainelli <f.fainelli@gmail.com>
>> Sent: 2021年8月5日 17:18
>> To: Joakim Zhang <qiangqing.zhang@nxp.com>; davem@davemloft.net;
>> kuba@kernel.org; robh+dt@kernel.org; shawnguo@kernel.org;
>> s.hauer@pengutronix.de; festevam@gmail.com; andrew@lunn.ch
>> Cc: kernel@pengutronix.de; dl-linux-imx <linux-imx@nxp.com>;
>> netdev@vger.kernel.org; devicetree@vger.kernel.org;
>> linux-kernel@vger.kernel.org; linux-arm-kernel@lists.infradead.org
>> Subject: Re: [PATCH net-next 1/3] dt-bindings: net: fsl, fec: add "fsl,
>> wakeup-irq" property
>>
>>
>>
>> On 8/5/2021 12:46 AM, Joakim Zhang wrote:
>>> Add "fsl,wakeup-irq" property for FEC controller to select wakeup irq
>>> source.
>>>
>>> Signed-off-by: Fugang Duan <fugang.duan@nxp.com>
>>> Signed-off-by: Joakim Zhang <qiangqing.zhang@nxp.com>
>>
>> Why are not you making use of the standard interrupts-extended property
>> which allows different interrupt lines to be originating from different interrupt
>> controllers, e.g.:
>>
>> interrupts-extended = <&gic GIC_SPI 112 4>, <&wakeup_intc 0>;
> 
> Thanks.
> 
> AFAIK, interrupts-extended should be used instead of interrupts when a device is connected to multiple interrupt controllers
> as it encodes a parent phandle with each interrupt specifier. However, for FEC controller, all interrupt lines are originating from
> the same interrupt controllers.

OK, so why this custom property then?

> 
> 1) FEC controller has up to 4 interrupt lines and all of these are routed to GIC interrupt controller.
> 2) FEC has a wakeup interrupt signal and always are mixed with other interrupt signals, and then output to one interrupt line.
> 3) For legacy SoCs, wakeup interrupt are mixed to int0 line, but for i.MX8M serials, are mixed to int2 line.
> 4) Now driver treat int0 as the wakeup source by default, it is broken for i.MX8M.

I don't really know what to make of your response, it seems to me that 
you are carrying some legacy Device Tree properties that were invented 
when interrupts-extended did not exist and we did not know any better.
-- 
Florian