On Friday 08 May 2009 09:52:51 David Miller wrote: > From: John Rigby <jcri...@gmail.com> > Date: Thu, 7 May 2009 20:02:53 -0600 > > > Also don't forget that the register map is the same on 512x, mx and > > coldfire platforms but not on the other ppc platforms so if you want > > to one binary to rule them all you will need to have an offest table > > or some such. > > I would suggest using ->read_reg() ->write_reg() methods for abstracting > this. That's how we handle all of the different way ESP scsi chips > have their registers wired up. > > I/O register reads take hundreds, if not thousands of CPU cycles so, > relatively speaking, the indirection costs absolutely nothing.
I fear the memory-mapped I/O of the PowerPC SoC is *slightly* faster, so in terms of cycle count, this WILL matter, although depending on how much register-I/O the driver does, overall performance impact _may_ still be negligible. I suggest testing this (benchmarks) before and after the change. Best regsards, -- David Jander Protonic Holland. _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@ozlabs.org https://ozlabs.org/mailman/listinfo/linuxppc-dev