[PATCH] RTC: TWL: ensure all interrupts are disabled during probe

Steve Sakoman steve at sakoman.com
Fri Sep 14 11:33:42 EDT 2012

On Thu, Sep 13, 2012 at 1:45 PM, Kevin Hilman
<khilman at deeprootsystems.com> wrote:
> From: Kevin Hilman <khilman at ti.com>
> On some platforms, bootloaders are known to do some interesting RTC
> programming.  Without going into the obscurities as to why this may be
> the case, suffice it to say the the driver should not make any
> assumptions about the state of the RTC when the driver loads.  In
> particular, the driver probe should be sure that all interrupts are
> disabled until otherwise programmed.
> This was discovered when finding bursty I2C traffic every second on
> Overo platforms.  This I2C overhead was keeping the SoC from hitting
> deep power states.  The cause was found to be the RTC firing every
> second on the I2C-connected TWL PMIC.
> Special thanks to Felipe Balbi for suggesting to look for a rogue
> driver as the source of the I2C traffic rather than the I2C driver
> itself.
> Special thanks to Steve Sakoman for helping track down the source of
> the continuous RTC interrups on the Overo boards.
> Cc: Felipe Balbi <balbi at ti.com>
> Cc: Steve Sakoman <steve at sakoman.com>
> Signed-off-by: Kevin Hilman <khilman at ti.com>

Tested on Overo/Tobi, and I no longer see the 1/second interrupts.
Also verified that alarm interrupts still work using rtcwake.

Tested-by: Steve Sakoman <steve at sakoman.com>

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