Date:   Wed, 11 Aug 2021 08:06:57 +0000
From:   Joakim Zhang <qiangqing.zhang@....com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kuba@...nel.org" <kuba@...nel.org>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>,
        "shawnguo@...nel.org" <shawnguo@...nel.org>,
        "s.hauer@...gutronix.de" <s.hauer@...gutronix.de>,
        "festevam@...il.com" <festevam@...il.com>,
        "andrew@...n.ch" <andrew@...n.ch>
CC:     "kernel@...gutronix.de" <kernel@...gutronix.de>,
        dl-linux-imx <linux-imx@....com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>
Subject: RE: [PATCH net-next 1/3] dt-bindings: net: fsl, fec: add "fsl,
 wakeup-irq" property


> -----Original Message-----
> From: Florian Fainelli <f.fainelli@...il.com>
> Sent: 2021年8月11日 1:45
> To: Joakim Zhang <qiangqing.zhang@....com>; davem@...emloft.net;
> kuba@...nel.org; robh+dt@...nel.org; shawnguo@...nel.org;
> s.hauer@...gutronix.de; festevam@...il.com; andrew@...n.ch
> Cc: kernel@...gutronix.de; dl-linux-imx <linux-imx@....com>;
> netdev@...r.kernel.org; devicetree@...r.kernel.org;
> linux-kernel@...r.kernel.org; linux-arm-kernel@...ts.infradead.org
> Subject: Re: [PATCH net-next 1/3] dt-bindings: net: fsl, fec: add "fsl,
> wakeup-irq" property
> 
> 
> 
> On 8/9/2021 7:21 PM, Joakim Zhang wrote:
> >
> > Hi Florian,
> >
> >> -----Original Message-----
> >> From: Florian Fainelli <f.fainelli@...il.com>
> >> Sent: 2021年8月10日 2:40
> >> To: Joakim Zhang <qiangqing.zhang@....com>; davem@...emloft.net;
> >> kuba@...nel.org; robh+dt@...nel.org; shawnguo@...nel.org;
> >> s.hauer@...gutronix.de; festevam@...il.com; andrew@...n.ch
> >> Cc: kernel@...gutronix.de; dl-linux-imx <linux-imx@....com>;
> >> netdev@...r.kernel.org; devicetree@...r.kernel.org;
> >> linux-kernel@...r.kernel.org; linux-arm-kernel@...ts.infradead.org
> >> Subject: Re: [PATCH net-next 1/3] dt-bindings: net: fsl, fec: add
> >> "fsl, wakeup-irq" property
> >>
> >>
> >>
> >> On 8/8/2021 10:08 PM, Joakim Zhang wrote:
> >>>
> >>> Hi Florian,
> >>>
> >>>> -----Original Message-----
> >>>> From: Florian Fainelli <f.fainelli@...il.com>
> >>>> Sent: 2021年8月5日 17:18
> >>>> To: Joakim Zhang <qiangqing.zhang@....com>; davem@...emloft.net;
> >>>> kuba@...nel.org; robh+dt@...nel.org; shawnguo@...nel.org;
> >>>> s.hauer@...gutronix.de; festevam@...il.com; andrew@...n.ch
> >>>> Cc: kernel@...gutronix.de; dl-linux-imx <linux-imx@....com>;
> >>>> netdev@...r.kernel.org; devicetree@...r.kernel.org;
> >>>> linux-kernel@...r.kernel.org; linux-arm-kernel@...ts.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@....com>
> >>>>> Signed-off-by: Joakim Zhang <qiangqing.zhang@....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.
> >
> > As I described in former mail, it is not related to interrupts-extended
> property.
> >
> > Let's take a look, e.g.
> >
> > 1) arch/arm/boot/dts/imx7d.dtsi
> > interrupts = <GIC_SPI 102 IRQ_TYPE_LEVEL_HIGH>,
> > 		<GIC_SPI 100 IRQ_TYPE_LEVEL_HIGH>,
> > 		<GIC_SPI 101 IRQ_TYPE_LEVEL_HIGH>,
> > 		<GIC_SPI 103 IRQ_TYPE_LEVEL_HIGH>;
> > interrupt-names = "int0", "int1", "int2", "pps";
> >
> > For these 4 interrupts are originating from GIC interrupt controller,
> > "int0" for queue 0 and other interrupt signals, containing wakeup; "int1" for
> queue 1; "int2" for queue 2.
> >
> > 2) arch/arm64/boot/dts/freescale/imx8mq.dtsi
> > interrupts = <GIC_SPI 118 IRQ_TYPE_LEVEL_HIGH>,
> > 	<GIC_SPI 119 IRQ_TYPE_LEVEL_HIGH>,
> > 	<GIC_SPI 120 IRQ_TYPE_LEVEL_HIGH>,
> > 	<GIC_SPI 121 IRQ_TYPE_LEVEL_HIGH>;
> > interrupt-names = "int0", "int1", "int2", "pps";
> >
> > For these 4 interrupts are also originating from GIC interrupt
> > controller, "int0" for queue 0; "int1" for queue 1; "int2" for queue 2 and other
> interrupt signals, containing wakeup.
> >
> > If we want to use WoL feature, we need invoke enable_irq_wake() to let
> > this specific interrupt line be a wakeup source. For FEC driver now,
> > it treats "int0" as wakeup interrupt by default. Obviously it's not fine for
> i.MX8M serials, since SoC mix wakeup interrupt signal into "int2", so I add this
> "fsl,wakeup-irq" custom property to indicate which interrupt line contains
> wakeup signal.
> >
> > Not sure if I have explained it clearly enough, from my point of view, I think
> interrupts-extended property can't fix this issue, right?
> 
> This is clearer, and indeed interrupts-extended won't fix that, however it seems
> to me that this is a problem that ought to be fixed at the interrupt
> controller/irq_chip level which should know and be told which interrupt lines
> can be made wake-up interrupts or not. From there on, the driver can test with
> enable_irq_wake() whether this has a chance of working or not.

How can we test with enable_irq_wake()? I agree that interrupt controller can recognize
wakeup interrupt is better. 

> It seems to me that the 'fsl,wakeup-irq' property ought to be within the
> interrupt controller Device Tree node (where it would be easier to validate that
> the specific interrupt line is correct) as opposed to within the consumer (FEC)
> Device Tree node.

Not quite understand, could you explain more?

> >
> > If there is any common properties can be used for it, please let me know. Or
> any other better solutions also be appreciated. Thanks.
> 
> There is a standard 'wakeup-source' boolean property that can be added
> to any Device Tree node to indicate it can be a wake-up source, but what
> you need here is a bitmask, so introducing a custom property may be
> appropriate here.

Yes, I know 'wakeup-source' boolean property that identify this DEVICE
can be a wakeup source, it's not related to interrupt.

Best Regards,
Joakim Zhang
> --
> Florian

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