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    SubjectRe: [PATCH 1/3] regulator: twl: Make sure we have access to powerbus before trying to write to it
    Hi!

    > According to the TRM, we need to enable i2c access to powerbus before
    > writing to it. Also, a new write to powerbus should not be attempted if
    > there is a pending transfer. The current code does not implement that
    > functionality and while there are no known problems caused by that, it is
    > better to follow what TRM says.
    >
    > Signed-off-by: Ivaylo Dimitrov <ivo.g.dimitrov.75@gmail.com>
    > ---
    > drivers/regulator/twl-regulator.c | 78 +++++++++++++++++++++++++++++++++++----
    > 1 file changed, 70 insertions(+), 8 deletions(-)
    >
    > diff --git a/drivers/regulator/twl-regulator.c b/drivers/regulator/twl-regulator.c
    > index 955a6fb..aad748b0 100644
    > --- a/drivers/regulator/twl-regulator.c
    > +++ b/drivers/regulator/twl-regulator.c
    > @@ -21,7 +21,7 @@
    > #include <linux/regulator/machine.h>
    > #include <linux/regulator/of_regulator.h>
    > #include <linux/i2c/twl.h>
    > -
    > +#include <linux/delay.h>
    >
    > /*
    > * The TWL4030/TW5030/TPS659x0/TWL6030 family chips include power management, a
    > @@ -188,6 +188,74 @@ static int twl6030reg_is_enabled(struct regulator_dev *rdev)
    > return grp && (val == TWL6030_CFG_STATE_ON);
    > }
    >
    > +#define PB_I2C_BUSY BIT(0)
    > +#define PB_I2C_BWEN BIT(1)
    > +
    > +/* Wait until buffer empty/ready to send a word on power bus. */
    > +static int twl4030_wait_pb_ready(void)
    > +{
    > +
    > + int ret;
    > + int timeout = 10;
    > + u8 val;
    > +

    Can we do this plain

    while (timeout--) {
    }...

    ? Also... if the bit is not immediately available, it will wait for
    1msec. Would it make sense to have timeout = 1000 but wait only 10usec
    each time or something?

    Thanks,
    Pavel

    > + do {
    > + ret = twl_i2c_read_u8(TWL_MODULE_PM_MASTER, &val,
    > + TWL4030_PM_MASTER_PB_CFG);
    > + if (ret < 0)
    > + return ret;
    > +
    > + if (!(val & PB_I2C_BUSY))
    > + return 0;
    > +
    > + mdelay(1);
    > + timeout--;
    > + } while (timeout);
    > +
    > + return -ETIMEDOUT;
    > +}

    --
    (english) http://www.livejournal.com/~pavelmachek
    (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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