[lm-sensors] pmbus driver

Vivek Bardia bardia.vivek at gmail.com
Thu Jun 23 11:15:52 CEST 2011


On 22 June 2011 15:12, Guenter Roeck <guenter.roeck at ericsson.com> wrote:
>
> On Wed, Jun 22, 2011 at 04:45:14AM -0400, Vivek Bardia wrote:
> > Hi Guenter,
> >
> > sorry for the delayed reply from my end.
> >
> > Right now I am under the constraint where I cannot share the datasheet. But
> > yes, the datasheet is going be out very soon. I shall update u about the same
> >
> > Can the pmbus driver be used to set output voltage from another driver in the
> > kernel space itself. what I understood about the pmbus driver is that it is
> > meant for monitoring and controlling. at my end if the monitoring is being done
> > by another entity(voltage regulator) and the controlling only needs to be done
> > by the PMIC then how do I go about? say I just want to use VOUT_TRIM command.
> >
> At least right now that is not supported. The current driver only supports hwmon
> functionality, ie pure monitoring; control is not implemented. A clean implementation
> for control would probably require a rewrite with a generic part (probably in mfd),
> control (probably in regulator) and monitoring (in hwmon).

But you do have pmbus_write_byte/pmbus_write_word_data calls. They are
only not exported right?
or is it that if these calls are made, it wont work the way it should

> Note that you can not have an I2C slave chip controlled by multiple entities.
> If you wrote or have a regulator driver, it has control over the chip, and hwmon access
> to it will not be possible.

what if I simply do not need any monitoring capabilities. I just want
to enable the device(OPERATION), read the output voltage(READ_VOUT)
and then based on an external custom sensor set the output
voltage(VOUT_TRIM), once done disable the device.

> Not sure what your application is. If it is for mfg testing (which the VOUT_TRIM command
> suggests), you might be better off just using raw I2C commands from user space (which again
> would only work while the chip is not 'claimed' by a kernel driver).

I want to use these few commands from the kernel space itself.

Regards,
Vivek




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