Subject: Re: fw_devlink on will break all snps,dw-apb-gpio users

From: Jisheng Zhang <[email-masked]>
Date: Thu, 15 Oct 2020 12:02:06 +0800

On Wed, 14 Oct 2020 10:29:36 -0700
Saravana Kannan <[email-masked]> wrote:

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> 
> 
> On Wed, Oct 14, 2020 at 4:12 AM Jisheng Zhang
> <[email-masked]> wrote:
> >
> > Hi,
> >
> > If set fw_devlink as on, any consumers of dw apb gpio won't probe.
> >
> > The related dts looks like:
> >
> > gpio0: gpio@2400 {
> >        compatible = "snps,dw-apb-gpio";
> >        #address-cells = <1>;
> >        #size-cells = <0>;
> >
> >        porta: gpio-port@0 {
> >               compatible = "snps,dw-apb-gpio-port";
> >               gpio-controller;
> >               #gpio-cells = <2>;
> >               ngpios = <32>;
> >               reg = <0>;
> >        };
> > };
> >
> > device_foo {
> >         status = "okay"
> >         ...;
> >         reset-gpio = <&porta, 0, GPIO_ACTIVE_HIGH>;
> > };
> >
> > If I change the reset-gpio property to use another kind of gpio phandle,
> > e.g gpio expander, then device_foo can be probed successfully.
> >
> > The gpio expander dt node looks like:
> >
> >         expander3: gpio@44 {
> >                 compatible = "fcs,fxl6408";
> >                 pinctrl-names = "default";
> >                 pinctrl-0 = <&expander3_pmux>;
> >                 reg = <0x44>;
> >                 gpio-controller;
> >                 #gpio-cells = <2>;
> >                 interrupt-parent = <&portb>;
> >                 interrupts = <23 IRQ_TYPE_NONE>;
> >                 interrupt-controller;
> >                 #interrupt-cells = <2>;
> >         };
> >
> > The common pattern looks like the devlink can't cope with suppliers from
> > child dt node.  
> 
> fw_devlink doesn't have any problem dealing with child devices being
> suppliers. The problem with your case is that the
> drivers/gpio/gpio-dwapb.c driver directly parses the child nodes and
> never creates struct devices for them. If you have a node with
> compatible string, fw_devlink expects you to create and probe a struct
> device for it. So change your driver to add the child devices as
> devices instead of just parsing the node directly and doing stuff with
> it.
> 
> Either that, or stop putting "compatible" string in a node if you
> don't plan to actually treat it as a device -- but that's too late for
> this driver (it needs to be backward compatible). So change the driver
> to add of_platform_populate() and write a driver that probes
> "snps,dw-apb-gpio-port".
> 

Thanks for the information. The "snps,dw-apb-gpio-port" is never used,
so I just sent out a series to remove it.

Thanks

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