On Mon, 2013-06-03 at 12:52 +0100, Lorenzo Pieralisi wrote: > On Mon, Jun 03, 2013 at 11:15:32AM +0100, Jon Medhurst (Tixy) wrote: > > On Fri, 2013-05-24 at 13:53 +0100, Lorenzo Pieralisi wrote: > > > In case some transactions to the Serial Power Controller (SPC) are lost > > > owing > > > to multiple operations handled at once by the M3 controller the OS needs > > > to > > > rely on a configuration API that can time out so that failures do not > > > result > > > in an unusable system. > > > > > > This patch adds a timeout API to the vexpress config programming > > > interface, > > > and refactors the existing read/write functions so that they can be reused > > > seamlessly on top of the newly defined API. > > > > Isn't one of the main purposes of the config interface to serialise > > transactions to the config bus, so why would the SPC be handling > > multiple transactions at once? And if we can in fact loose transactions > > doesn't this mean we get random failures in the system? E.g. if this > > happened at boot in vexpress_spc_populate_opps then cpufreq will fail. > > It has more to do with firmware carrying out background operations like > powering up a cluster when a DVFS is requested.
Would that make it drop transactions or just take a longer time to get around to servicing them? > I can prepare a v2 with timeout interface dropped and extensively test that > one, I do not think we should add the required complexity that you describe > below for something that should never happen. > > > Also, I think the code implementing timeouts is broken, see below. > > I will have a look asap and repost a v2 accordingly. Thanks, I'll hold off any further review the current patches then. -- Tixy -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
