On 14/08/13 12:37, Benjamin Herrenschmidt wrote: > On Wed, 2013-08-14 at 11:01 +0100, Sudeep KarkadaNagesha wrote: >> Yes this doesn't cover the historical "ibm,ppc-interrupt-server#s", >> for >> which we can have PPC specific wrapper above the generic one i.e. get >> the cpu node and then parse for thread id under custom property. > > A wrapper is wrong. I don't want to have to have all ppc callers to use > a different function. Ok. On the side note the main intention of this patch series[1] is to avoid calling of_get_cpu_node function once CPU devices are registered. It initialises the of_node in all the cpu devices using this function when registering the CPU device. It can be retrieved from cpu_dev->of_node. So direct users of of_get_cpu_node can be reduced to avoid unnecessary parsing of DT to find cpu node. > > As I said, just make a generic one that returns a thread ID, ie, same > signature as the powerpc one. Make it weak, we can override it in > powerpc-land, IMO, making generic definition which adhere to the ePAPR specification as weak is not so clean. > or we can move the ibm,ppc-interrupt-server#s handling > into the generic one, it won't hurt, but leave the thread_id return > there, it doesn't hurt it will come in handy in a few cases without > causing code duplication. > IMO moving of handling ibm,ppc-interrupt-server#s to generic code under #ifdef CONFIG_PPC seems to be cleaner approach than weak definitation. As per my understanding each thread is a different logical cpu. Each logical cpu is mapped to unique physical id(either present in reg field or legacy ibm,ppc-interrupt-server#s field). So given a logical cpu id we can get the cpu node corresponding to it. Looking @ smp_setup_cpu_maps in arch/powerpc/kernel/setup-common.c and the comment in the same file: "This implementation only supports power of 2 number of threads.." the thread id id is implicit in the logical cpu id. Do we need to fetch that from DT ? Regards, Sudeep [1] https://lkml.org/lkml/2013/7/22/219 -- 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
