On 02/18, Shawn Lin wrote: > set_phase does sanity checking of degree and ask sub-driver > to set the degree. If set_phase is limited to support the > degree what the caller need, sub-driver may select a > approximate value and return success state. In this case, it's > inappropriate to assign the degree directly to clk->core->phase. > We should ask sub-driver to decide the strategy. If sub-driver just > want to support accurate degree, it can fail the set_phase. Otherwise, > store the actual degree provided by sub-driver into clk->core->phase > if get_phase is provided. Another improvemnt by this patch is that > we can avoid to do unnecessary set_phase if the request defrees is > already there. > > Signed-off-by: Shawn Lin <[email protected]> > > ---
Knee jerk reaction is why does the provider code set a phase that isn't requested? Do we need some sort of clk_round_phase() API that parallels clk_round_rate() so that drivers know what phase they're going to get? Or do drivers not care what phase they get when they call clk_set_phase()? > > Changes in v2: > - remove actual_degree to simplify the changes > - bail early if nothing to to > > drivers/clk/clk.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > > diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c > index b4db67a..275e70f 100644 > --- a/drivers/clk/clk.c > +++ b/drivers/clk/clk.c > @@ -1902,6 +1902,10 @@ int clk_set_phase(struct clk *clk, int degrees) > > clk_prepare_lock(); > > + /* bail early if nothing to do */ > + if (degrees == clk->core->phase) > + goto out; > + This could be split out into a different "optimization" patch and applied today. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
