Let's update and clarify he phy documentation, to reflect the latest changes around the runtime PM deployment in the phy core. Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: linux-doc@xxxxxxxxxxxxxxx Signed-off-by: Ulf Hansson <ulf.hansson@xxxxxxxxxx> --- Documentation/phy.txt | 29 ++++++++++++++++------------- 1 file changed, 16 insertions(+), 13 deletions(-) diff --git a/Documentation/phy.txt b/Documentation/phy.txt index 457c3e0..1c2c761 100644 --- a/Documentation/phy.txt +++ b/Documentation/phy.txt @@ -160,19 +160,22 @@ associated with this PHY. PM Runtime ========== -This subsystem is pm runtime enabled. So while creating the PHY, -pm_runtime_enable of the phy device created by this subsystem is called and -while destroying the PHY, pm_runtime_disable is called. Note that the phy -device created by this subsystem will be a child of the device that calls -phy_create (PHY provider device). - -So pm_runtime_get_sync of the phy_device created by this subsystem will invoke -pm_runtime_get_sync of PHY provider device because of parent-child relationship. -It should also be noted that phy_power_on and phy_power_off performs -phy_pm_runtime_get_sync and phy_pm_runtime_put respectively. -There are exported APIs like phy_pm_runtime_get, phy_pm_runtime_get_sync, -phy_pm_runtime_put, phy_pm_runtime_put_sync, phy_pm_runtime_allow and -phy_pm_runtime_forbid for performing PM operations. +This subsystem deploys runtime PM support. More precisely, calls to +pm_runtime_get_sync() and to pm_runtime_put() surrounds calls to the phy +provider callbacks, ->init|exit(), in phy_init|exit(). At phy_power_on(), the +runtime PM usage count is raised again, via pm_runtime_get_sync(). The usage +count remain raised, until the internal phy power on count reaches zero in +phy_power_off(), at which point pm_runtime_put() is called to restore the +runtime PM usage count. In this way, the device is guranteed to stay runtime +resumed as long as the phy is powered on. + +In regards to the runtime PM deployment in the phy core, it should also be +noted that it's deployed for the phy provider device, which is the parent of +the phy child device. In other words, the phy device created by the phy core +remains runtime PM disabled. Of course, whether runtime PM is really used or +not, depends on whether the phy provider driver has enabled runtime PM for its +provider device. More exactly, pm_runtime_enable() needs to be called prior +calling phy_create() or devm_phy_create(). PHY Mappings ============ -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
