• Nishanth Menon's avatar
    regulator: ti-abb: Fix bias voltage glitch in transition to bypass mode · bf00ca35
    Nishanth Menon authored
    As documented in Application Note SWPA117 v2.1(NDA), LDO override has a
    requirement that when switching from Bias active + override active
    mode(FBB/RBB) to Bypass(nominal) mode, LDO reset must be performed
    *after* LDO transitions to Bypass(nominal) mode.
    
    The same rule in reverse applies when switching from a ABB bypass mode
    to ABB enabled - LDO override *must* be performed prior to transition to
    required ABB mode, if we do not do that, the same glitch takes place.
    
    Currently while transitioning to ABB bypass, we reset the LDO overide
    prior to the transition which causes a few milliseconds where ABB LDO
    voltage could go all the way to 800mV(based on SoC process node),
    during this period, the delta voltage between VDD rail and VBB rail
    could cause the system to improperly function.
    Signed-off-by: default avatarNishanth Menon <nm@ti.com>
    Signed-off-by: default avatarMark Brown <broonie@linaro.org>
    Cc: stable@vger.kernel.org
    bf00ca35
ti-abb-regulator.c 23.8 KB