Messages in this thread | | | Date | Tue, 15 Feb 2011 08:37:59 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [RFC,PATCH 1/3] Add a common struct clk |
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On Tue, Feb 15, 2011 at 03:26:53PM +0800, Jeremy Kerr wrote: > Hi Saravana, > > > Sure, one could argue that in some archs for a certain set of clocks the > > slow stuff in prepare/unprepare won't need to be done during set rate -- > > say, a simple clock that always runs off the same PLL but just has a > > integer divider to change the rate. > > > > In those cases, not grabbing the prepare_lock would make the code less > > "locky". > > > > > We > > > may even want to disallow set_rate (and set_parent) when prepare_count is > > > non- zero. > > > > This is definitely not right. > > Why is that? Consider two devices using one clock; one does some > initialisation based on the return value of clk_get_rate(), the other calls > clk_set_rate() some time later. Now the first device is incorrectly > initialised.
What about a clock sourced from a PLL which provides the dotclock for a framebuffer device? On every mode set, should the clk have to be disabled, unprepared, rate set, re-prepared and re-enabled?
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