On 2016-11-11 12:47, MikeB wrote: > On Thu, Nov 10, 2016 at 8:01 AM, Peter Rosin <peda@xxxxxxxxxx> wrote: >>> There is however one requirement, the CPLD-mux must be "mux-locked" >>> as explained in Documentation/i2c/i2c-topology. Otherwise accesses >>> to devices behind that mux will lock the PCA9547 mux for the full >>> duration of the transaction and thus lock out any attempts to update >>> the CPLD mux as part of the transaction. > > Thank you for the informative reply. I was unfamiliar with the new > mux and parent locking schemes. They do make the solution for this > problem much easier to deal with. I'm working with release 4.4 > (Ubuntu Xenial), so the mux/parent locking hadn't shown up on my radar > yet. Unfortunately, the target release for my work is and will remain > 4.4 for a while. Lucky you :-) Anyway, you might be able to backport the changes? Start with: a7ab72390b77062420fb50e4451f71c9321aae05 "i2c: mux: add common data for every i2c-mux instance" through to 23fe440c59b9f08afe108e7ec7b6714cb2a3b955 "i2c: mux: drop old unused i2c-mux api" And then: 785d32c7a9638a96730686663564d1842f7c2f03 "i2c: allow adapter drivers to override the adapter locking" through to f76b724ee915415c52068c622ca48c652c1bd10c "i2c-mux: document i2c muxes and elaborate on parent-/mux-locked muxes" There are a handful of commits right after that that are also related, but they should be irrelevant to you... Haven't tried it though, YMMV, and I might have forgotten a patch or two that came in later, but I don't remember any serious fallout... Cheers, Peter -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
