Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH 02/14] dt-bindings: soc: milbeaut: Add Milbeaut trampoline description | From | "Sugaya, Taichi" <> | Date | Tue, 4 Dec 2018 20:30:53 +0900 |
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Hi
On 2018/12/04 0:49, Rob Herring wrote: > On Mon, Dec 3, 2018 at 1:42 AM Sugaya, Taichi > <sugaya.taichi@socionext.com> wrote: >> >> Hi, >> >> On 2018/11/30 17:16, Stephen Boyd wrote: >>> Quoting Sugaya, Taichi (2018-11-29 04:24:51) >>>> On 2018/11/28 11:01, Stephen Boyd wrote: >>>>> Quoting Sugaya Taichi (2018-11-18 17:01:07) >>>>>> create mode 100644 Documentation/devicetree/bindings/soc/socionext/socionext,m10v.txt >>>>>> >>>>>> diff --git a/Documentation/devicetree/bindings/soc/socionext/socionext,m10v.txt b/Documentation/devicetree/bindings/soc/socionext/socionext,m10v.txt >>>>>> new file mode 100644 >>>>>> index 0000000..f5d906c >>>>>> --- /dev/null >>>>>> +++ b/Documentation/devicetree/bindings/soc/socionext/socionext,m10v.txt >>>>>> @@ -0,0 +1,12 @@ >>>>>> +Socionext M10V SMP trampoline driver binding >>>>>> + >>>>>> +This is a driver to wait for sub-cores while boot process. >>>>>> + >>>>>> +- compatible: should be "socionext,smp-trampoline" >>>>>> +- reg: should be <0x4C000100 0x100> >>>>>> + >>>>>> +EXAMPLE >>>>>> + trampoline: trampoline@0x4C000100 { >>>>> Drop the 0x part of unit addresses. >>>> >>>> Okay. >>>> >>>> >>>>>> + compatible = "socionext,smp-trampoline"; >>>>>> + reg = <0x4C000100 0x100>; >>>>> Looks like a software construct, which we wouldn't want to put into DT >>>>> this way. DT doesn't describe drivers. >>>> We would like to use this node only getting the address of the >>>> trampoline area >>>> in which sub-cores wait. (They have finished to go to this area in previous >>>> bootloader process.) >>> >>> Is this area part of memory, or a special SRAM? If it's part of memory, >>> I would expect this node to be under the reserved-memory node and >>> pointed to by some other node that uses this region. Could even be the >>> CPU nodes. >> >> Yes, 0x4C000100 is a part of memory under the reserved-memory node. So >> we would like to use the SRAM ( allocated 0x00000000 ) area instead. >> BTW, sorry, the trampoline address of this example is simply wrong. We >> were going to use a part of the SRAM from the beginning. >> >>> >>>> >>>> So should we embed the constant value in source codes instead of getting >>>> from >>>> DT because the address is constant at the moment? Or is there other >>>> approach? >>>> >>> >>> If it's constant then that also works. Why does it need to come from DT >>> at all then? >> >> We think it is not good to embed constant value in driver codes and do >> not have another way... >> Are there better ways? > > If this is just memory, can you use the standard spin-table binding in > the DT spec? There are some requirements like 64-bit values even on > 32-bit machines (though this gets violated).
The spin-table seems to be used on only 64-bit arch. Have it ever worked on 32-bit machine? And I would like not to use it because avoid violation.
Thanks Sugaya Taichi
> > Rob >
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