Re: [Xen-devel] [PATCH V6] xen: arm: platforms: Adding reset support for xgene arm64 platform.

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Tue, 2014-01-28 at 23:05 +0530, Pranavkumar Sawargaonkar wrote:
> Hi Ian,
> 
> On 28 January 2014 21:17, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> > On Mon, 2014-01-27 at 17:04 +0530, Pranavkumar Sawargaonkar wrote:
> >> +        DT_MATCH_COMPATIBLE("apm,xgene-reboot"),
> >
> > I should have asked this sooner -- can you point me to the bindings
> > documentation for this device?
> >
> > http://www.gossamer-threads.com/lists/linux/kernel/1845585 suggests it
> > is not yet agreed, so having Xen depend on it may have been a mistake.
> 
> Above patch is still under discussion so i can not take changes from
> that to xen driver immediately.
> 
> For now i have added xen reset code based on
> "drivers/power/reset/xgene-reboot.c" driver which is already merged in
> linux.
> 
> http://www.spinics.net/lists/arm-kernel/msg266039.html
> For now DTS bindings for xen are similar as mentioned in above link.
> 
> Actually if you see new patch and old one (from reboot point of view) -
> Only difference in both the dts bindings is "mask" filed in dts.
> In old patch it used to be read from dts but in latest it is
> hard-coded to 1 in actual code and being removed from dts in new
> patch.

Do you have a ref for that new patch?

I also don't see any patch to linux/Documentation/devicetree/bindings,
as was requested in that posting from 6 months ago. Where can I find
that?

It seems like the patch to arch/arm64/boot/dts/apm-storm.dtsi also
hasn't landed?

> Now if you want this to be fixed , i can quickly submit a V7 in which
> mask field will be just hard-coded to 1 hence xen code will always
> work even if linux code does gets changed.

Looks like the Linux driver uses 0xffffffff if the mask isn't given --
that seems like a good approach.

I think we'll just have to accept that until the binding is specified
and documented (in linux/Documentation/devicetree/bindings) then we may
have to be prepared to change the Xen implementation to match the final
spec without regard to backwards compat. If we aren't happy with that
then I should revert the patch now and we will have to live without
reboot support in the meantime.

Ian


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