• Jean-Francois Dagenais's avatar
    drivers/w1/slaves/w1_ds2408.c: add magic sequence to disable P0 test mode · d5528773
    Jean-Francois Dagenais authored
    Power-up timing
    
    The DS2408 is sensitive to the power-on slew rate and can inadvertently
    power up with a test mode feature enabled.  When this occurs, the P0 port
    does not respond to the Channel Access Write command.  For most reliable
    operation, it is recommended to disable the test mode after every power-on
    reset using the Disable Test Mode sequence shown below.  The 64-bit ROM
    code must be transmitted in the same bit sequence as with the Match ROM
    command, i.e., least significant bit first.  This precaution is
    recommended in parasite power mode (VCC pin connected to GND) as well as
    with VCC power.
    
    Disable Test Mode:
    RST,PD,96h,<64-bit DS2408 ROM Code>,3Ch,RST,PD
    
    [akpm@linux-foundation.org: don't use kerenldoc token to introduce a non-kerneldoc comment, tweak whitespace]
    Signed-off-by: default avatarJean-Francois Dagenais <jeff.dagenais@gmail.com>
    Cc: Evgeniy Polyakov <zbr@ioremap.net>
    Cc: Greg KH <greg@kroah.com>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    d5528773
w1_ds2408.c 10.5 KB