On Feb 25, 2014, at 5:16 AM, Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx> wrote: > Hi Stephen, > > On Wed, Feb 19, 2014 at 12:20:43AM +0000, Stephen Boyd wrote: >> (Sorry, this discussion stalled due to merge window + life events) > > Sorry for the delay in replying on my side too. > >> On 01/17, Lorenzo Pieralisi wrote: >>> On Thu, Jan 16, 2014 at 07:26:17PM +0000, Stephen Boyd wrote: >>>> On 01/16, Lorenzo Pieralisi wrote: >>>>> On Thu, Jan 16, 2014 at 06:05:05PM +0000, Stephen Boyd wrote: >>>>>> On 01/16, Lorenzo Pieralisi wrote: >>>>>>> Do we really want to do that ? I am not sure. A cpus node is supposed to >>>>>>> be a container node, we should not define this binding just because we >>>>>>> know the kernel creates a platform device for it then. >>>>>> >>>>>> This is just copying more of the ePAPR spec into this document. >>>>>> It just so happens that having a compatible field here allows a >>>>>> platform device to be created. I don't see why that's a problem. >>>>> >>>>> I do not see why you cannot define a node like pmu or arch-timer and stick >>>>> a compatible property in there. cpus node does not represent a device, and >>>>> must not be created as a platform device, that's my opinion. >>>>> >>>> >>>> I had what you're suggesting before in the original revision of >>>> this patch. Please take a look at the original patch series[1]. I >>>> suppose it could be tweaked slightly to still have a cache node >>>> for the L2 interrupt and the next-level-cache pointer from the >>>> CPUs. >>> >>> Ok, sorry, we are running around in circles here, basically you moved >>> the node to cpus according to reviews. I still think that treating cpus >>> as a device is not a great idea, even though I am in the same >>> position with C-states and probably will add C-state tables in the cpus >>> node. >>> >>> http://comments.gmane.org/gmane.linux.power-management.general/41012 >>> >>> I just would like to see under cpus nodes and properties that apply to >>> all ARM systems, and avoid defining properties (eg interrupts) that >>> have different meanings for different ARM cores. >>> >>> The question related to why the kernel should create a platform device >>> out of cpus is still open. I really do not want to block your series >>> for these simple issues but we have to make a decision and stick to that, >>> I am fine either way if we have a plan. >>> >> >> Do you just want a backup plan in case we don't make a platform >> device out of the cpus node? I believe we can always add code >> somewhere to create a platform device at runtime if we detect the >> cpus node has a compatible string equal to "qcom,krait". We could >> probably change this driver's module_init() to scan the DT for >> such a compatible string and create the platform device right >> there. If we get more than one interrupt in the cpus node we can >> add interrupt-names and then have software look for interrupts by >> name instead of number. > > As I mentioned, I do not like the idea of adding compatible properties > just to force the kernel to create platform devices out of device tree > nodes. On top of that I would avoid adding a compatible property > to the cpus node (after all properties like enable-method are common for all > cpus but still duplicated), my only concern being backward compatibility > here (ie if we do that for interrupts, we should do that also for other > common cpu nodes properties, otherwise we have different rules for > different properties). > > I think you can then add interrupts to cpu nodes ("qcom,krait" specific), > and as you mentioned create a platform device for that. > > Thanks, > Lorenzo So I agree with the statement about adding compatibles just to create platform devices is wrong. However its seems perfectly reasonable for a cpu node to have a compatible property. I don’t see why a CPU is any different from any other device described in a DT. - k -- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
