Re: [PATCH 6/7] iio: mlx90614: Add power management

[Jonathan Cameron <jic23-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>]

On 09/03/15 16:43, Wolfram Sang wrote:
> On Mon, Mar 09, 2015 at 03:39:35PM +0000, Jonathan Cameron wrote:
>> On 25/02/15 15:55, Vianney le Clément de Saint-Marcq wrote:
>>> Add support for system sleep and runtime power management.
>>>
>>> To wake up the device, the SDA line should be held low for at least 33ms
>>> while SCL is high.  As this is not possible using the i2c API (and not
>>> supported by all i2c adapters), a GPIO connected to the SDA line is
>>> needed.  The GPIO is named "wakeup" and can be specified in a device
>>> tree with the "wakeup-gpios" binding.
>> Needs some i2c specialist input on this!  As you mentioned it is liable
>> to be controversial.  Wolfram, is this a one off special or do
>> any other devices do this sort of magic?
> 
> s/magic/insanity/ :)
> 
> I have never heard of something like this. Unsuprisingly, I can
> not recommend doing it this way. But we all know hardware...
> 
> And while we could think about reusing the bus_recovery_infrastructure,
> I don't think it is worth the hazzle. So, doing this GPIO fallback may
> well be the best we can do now.
> 
Fair enough.  Lets go with this approach then and hope this is the only bit
of hardware ever to do this (yeah right ;)