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

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:

quoted

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.