Messages in this thread | | | Subject | Re: [PATCH v2] clk: check the actual phase if get_phase is provided | From | Shawn Lin <> | Date | Mon, 29 Feb 2016 09:14:52 +0800 |
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On 2016/2/27 8:10, Stephen Boyd wrote: > On 02/26, Shawn Lin wrote: >> On 2016/2/26 7:14, Stephen Boyd wrote: >>> On 02/18, Shawn Lin wrote: >>>> set_phase does sanity checking of degree and ask sub-driver >> >> [...] >> >>>> already there. >>>> >>>> Signed-off-by: Shawn Lin <shawn.lin@rock-chips.com> >>>> >>>> --- >>> >>> 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()? >> >> Hi Stephen, >> >> drivers should care what phase they get when calling clk_set_phase(i.e >> the drivers setting phase to do tuning work should know what the actual >> degrees is, which is important for them to decide the sample window >> algorithm). >> >> By looking into the two drivers who use set_phase/get_phase pair >> currently, they actually both don'e care what the actual degrees when >> they call clk_set_phase. I think that is because the drivers are used >> for specific platform which support 0~360 implicitly. But the situation >> is NOT always right for cross-platform drivers. So add some sort of >> round_phase API is probably sane ? >> > > Do you have such a platform or driver though? I'd rather not do > anything unless we actually need to.
Currently no, but we going to have one soon in this year which supports 10°, 20°, 30°,... 360°(each 10° a step, totally 36 steps). So I look into phase stuff in advance and send a RFC patch to discuss the practicability before I actually writing driver code.
I have no idea whether we need it. Or maybe we can just do some tricks inside current ->set_phase/get_phase call back to meet the requirment. Otherwise, I'd rather not add New API either.
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-- Best Regards Shawn Lin
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