---
- branch: MAIN
  date: Tue May 15 02:02:18 UTC 2018
  files:
  - new: '1.58'
    old: '1.57'
    path: src/sys/dev/i2c/i2c.c
    pathrev: src/sys/dev/i2c/i2c.c@1.58
    type: modified
  id: 20180515T020218Z.a481c5d8a6399420f42cb1e3f8afa82c0fd141c2
  log: |
    Fix a problem reported by jmcneill@ where by a system with multuple i2c
    busses would end up with "ghost" device instances on the second bus.  This
    issue was previously masked on ARM systems by the empty-child-devices
    array issue fixed recently (that effectively blocked all indirect config
    of i2c busses on those systems).

    To fix this problem, we require that indirectly-configured devices have
    to fully specify their parent spec and address, e.g.:

    foo* at iic0 addr 0x55

    NOT

    foo* at iic? addr ?

    or even:

    foo* at iic? addr 0x55

    This is needed because of how indirect configuration works... attach
    directives in the kernel config file are enumerated, calling the bus's
    search routine, which in the case of i2c, enumerates all i2c addresses
    and calls the match routine for each address.  Because we can't always
    reliably probe for i2c devices, we ended up with erroneous matches.

    Direct configuration of i2c is still allowed to use wildcarded parent specs
    and locators.
  module: src
  subject: 'CVS commit: src/sys/dev/i2c'
  unixtime: '1526349738'
  user: thorpej