On 22/08/13 12:59, Mark Rutland wrote: > On Wed, Aug 21, 2013 at 11:48:12PM +0100, Stephen Warren wrote: >> On 08/20/2013 04:00 AM, Sudeep KarkadaNagesha wrote: >> ... >>> Until we get more feedback and agreement on new proposal can we have >>> this simple amendment in this patch to the existing binding ? Since the >>> new proposal[1] is backward compatible(this patch adding support for >>> option#5 to existing option#1), we will have to add support for other >>> binding options in [1] later. >>> >>> This is needed to support shared OPPs with simple/single OPP profile >>> and also to fix the broken and unused binding >>> @Documentation/devicetree/bindings/cpufreq/arm_big_little_dt.txt >>> >>> Regards, >>> Sudeep >>> >>> [1] http://www.spinics.net/lists/cpufreq/msg06563.html >> >> Presumably the desire for cpu1's node to say "go look at cpu0's node for >> OPP" is because they share OPPs. Don't they share OPPs because they are >> parts of the same device - that device being the CPU complex. As such, >> why not define the OPPs in /cpus rather than in each of /cpus/cpuN? > > I'd very much like for it to be possible to factor out common properties > into the /cpus node, but it should follow the ePAPR recommendation fo > being treated as a fallback if not present in a particular /cpus/cpu@N > node -- that way we can handle clusters with differing OPPs. The > property might just be a phandle to a table node, but it should be > possible to make it common. > Yes we can have this fallback mechanism, but only from cpu devices(OPP library handles non-cpu devices too). Referring the table node, I have a generic question on DT nodes. Does each DT node have to represent a unique device ? If so having a property common to one/more devices in a separate node doesn't sound correct. >> >> Of course, that doesn't help if there are separate CPU and GPU nodes >> that just happen to have the same set of OPPs and you want to share them >> to save DT space. Is that at all likely? > > I suspect that the OPPs for CPUs and GPUs are likely to be quite > distict, and they are logically separate regardless. I'm not averse to > sharing of tables if we can handle them in a standard fashion. > IMO sharing OPPs just for saving DT space might lead to confusions(no strong opinion though). >> >> I'd suggest/bike-shed that operating-points-device is not the correct >> property name; it somehow implies that the other device actively defines >> the OPPs for this device, rather than just happening to have the same >> OPPs. Perhaps "operating-points-identical-to"? >> > > I'd rather not have properties that point elsewhere and say "treat me > the same as this node". I'd rather we have common properties as > described above. > Agreed, but for platforms with multiple CPU clusters, since we have only one /cpus node, we ned to have table node which is arguable if node has represent a device(as mentioned above) Regards, Sudeep -- 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
