Quoting Paul Cercueil (2021-03-07 09:07:41) > The purpose of this function is to be used along with the notifier > mechanism. > > When a parent clock can see its rate externally changed at any moment, > and a driver needs a specific clock rate to function, it can register a > notifier on the parent clock, and call clk_set_rate() on the base clock > to adjust its frequency according to the new parent clock. Can the driver use the rate locking mechanism to get a certain rate instead of registering for notifiers and trying to react to changes? > > This works fine, until the base clock has the CLK_SET_RATE_PARENT flag > set. In that case, calling clk_set_rate() on the base clock will call > clk_set_rate() on the parent clock, which will trigger the notifier > again, and we're in a loop. > > For that reason, we need to register the notifier on the parent clock of > the first ancestor of the base clock that will effectively modify its > rate when clk_set_rate() is called, which we can now obtain with > clk_get_first_to_set_rate(). > > Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
