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

[Pranavkumar Sawargaonkar <pranavkumar@xxxxxxxxxx>]

Hi Ian,

On 28 January 2014 23:13, Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:
> 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?
New patch is the one you have mentioned i.e.
http://www.gossamer-threads.com/lists/linux/kernel/1845585
It has new DT bindings.
>

> 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?
Yeah it is dangling and since new patch is already posted i think we
can wait for final DT bindings.
>
>> 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.
Please do not revert the patch , I think we can go ahead with current patch.
Once linux side is concluded i will fix minor changes in xen code
based on new DT bindigs..
>
> Ian
>
Thanks,
Pranav

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