Re: [RFC][PATCH] misc: Introduce reboot_reason driver

From: Sascha Hauer
Date: Wed Dec 09 2015 - 03:50:25 EST


On Tue, Dec 08, 2015 at 04:13:35PM -0800, John Stultz wrote:
> On Tue, Dec 8, 2015 at 1:52 PM, Arnd Bergmann <arnd@xxxxxxxx> wrote:
> >
> > On Tuesday 08 December 2015 13:29:22 John Stultz wrote:
> >
> > > diff --git a/arch/arm/boot/dts/qcom-apq8064-nexus7-flo.dts b/arch/arm/boot/dts/qcom-apq8064-nexus7-flo.dts
> > > index 5183d18..ee5dcb7 100644
> > > --- a/arch/arm/boot/dts/qcom-apq8064-nexus7-flo.dts
> > > +++ b/arch/arm/boot/dts/qcom-apq8064-nexus7-flo.dts
> > > @@ -282,6 +282,15 @@
> > > };
> > > };
> > >
> > > + reboot_reason: reboot_reason@2a03f65c {
> > > + compatible = "reboot_reason";
> >
> > This is not a good compatible string. There should generally be a vendor
> > name associated with it (use "linux," if nothing else, and you should have
> > '-' instead of '_'.
>
>
> Ack.
>
>
> >
> >
> > > + reg = <0x2A03F65C 0x4>;
> >
> > This may easily conflict with the device it is part of. We should have
> > non-overlapping register areas in general. For the example you are
> > looking at, which register block is this?
>
> So Bjorn says its IMEM, but I was assuming it was just a reserved
> magic phys addr from the bootloader.
>
> Ideally I'm hoping to use this same driver for another device, which
> plans to reserve a page from memory that the bootloader won't clear.
>
>
> > > +/* Types of reasons */
> > > +static enum {
> > > + NONE,
> > > + BOOTLOADER,
> > > + RECOVERY,
> > > + OEM,
> > > + MAX_REASONS
> > > +} __maybe_unused reason_types;
> >
> > The variable seems to always be unused, not just "__maybe_unused". Maybe remove it?
>
>
> Yea. I initially just had the empty enum, but the compiler was giving
> me "useless class storage specifier in empty declaration" warnings. So
> I added a variable to it, but then I got unused variable warnings. So
> I ended up with this. :P
>
> Is there a better way? Are enums for array indexes out of fashion?

They are not, but you have declared a variable (reason_types) which you
don't use. You probably meant to create a enum named reason_types, like
this:

enum reason_types {
NONE,
BOOTLOADER,
RECOVERY,
OEM,
MAX_REASONS
};

Sascha

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