On Wed, 16 Dec 2015, Wolfram Sang wrote:

> From: Wolfram Sang <wsa+rene...@sang-engineering.com>
> When we also are I2C slave, we need to disable runtime PM because the
> address detection mechanism needs to be active all the time. However, we
> can reenable runtime PM once the slave instance was unregistered. So,
> use pm_runtime_disable/enable to achieve this, since it has proper
> refcounting. pm_runtime_allow/forbid is like a global switch which is
> unsuitable here.
> Signed-off-by: Wolfram Sang <wsa+rene...@sang-engineering.com>
> ---
> I'd be grateful to get an ACK from a runtime PM expert to verify that my
> assumptions match reality :)

Yes, disabling runtime PM will do what you want.  However you might 
consider using pm_runtime_get_sync() and pm_runtime_put() instead, 
because pm_runtime_enable() does not check to see if the device is idle 
and can be suspended right away.  Alternatively, you can call 
pm_runtime_idle() after pm_runtime_enable().

pm_runtime_allow/forbid is even more unsuitable than you said, because
it can be overridden by the user.

Alan Stern

To unsubscribe from this list: send the line "unsubscribe linux-i2c" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Reply via email to