On 02-06-18, 01:14, Olof Johansson wrote: > And what I am saying is that it sounds like a broken binding if you don't allow > that, especially since it'll be a super common case that all CPUs will specify > the same cooling-device specifier. I am fine with allowing the #cooling-cells property in the cpus node if the DT maintainers are fine with it. @Rob: comments ? @Olof: What about other properties which are still going to be duplicated for the most common cases today, like: clocks, supply information, cache information, cpu-idle-states and others. When we can duplicate these properties, why not keep following the same for #cpu-cooling property ? Note that the OPP table doesn't really need to get duplicated (for new platforms) as the platforms use the v2 bindings now which just duplicates a phandle assignment for all CPUs. Its a mess with older platforms which use the earlier version of OPP table. > > This property is required to declare a device as a cooling-device and > > the device here is CPU. We use it as a cooling device by limiting its > > higher range of frequencies, so that it doesn't generate too much > > heat. > > > > It is already there for CPU0 and CPU4, but it should really be there > > for all the CPUs, like we have clock, supply, caches, etc. > > You have #cooling-cells in the cpu node, but the actual data is in the > thermal-zones nodes. Why isn't #cooling-cells under thermal-zones, next to > cooling-maps? Actually I thought about that when I worked on these patches initially and this is why I felt convinced that the CPU nodes are the right place for this. We add #interrupt-cells to an Interrupt controller's DT node, #gpio-cells to a GPIO controller's DT node, #clock-cells to a clock controller's DT node and that's exactly why we should (and we do) add #cooling-cells property to a cooling device's DT node. This information is used in two ways, first it enables the OS to know that the device is capable of being a cooling device and second it tells us how many arguments will be required with a phandle of this device. And so the cooling-maps always contain two arguments with the cooling device's phandle (which is mostly a CPU or a gpio fan) as the #cooling-cells currently is fixed to 2. And so I am not really sure if thermal-zones is the right place to define this thing. Is my understanding correct ? -- viresh -- 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
