On Thu, Dec 1, 2011 at 6:42 AM, Mark Brown <broonie@xxxxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > On Wed, Nov 30, 2011 at 11:39:59PM -0700, Paul Walmsley wrote: > >> Clock rate/parent-change notifiers are requirements for DVFS use-cases, >> and they must be paired with something like the >> clk_{allow,block}_rate_change() functions to work efficiently. I intend >> to comment on this later; it's not a simple problem. It might be worth >> noting that Tero and I implemented a simplified version of this for the >> N900. > > I'm thinking that if we're going to have clk_{allow,block}_rate_change() > we may as well make that the main interface to enable rate changes - if > a device wants to change the clock rate it allows rate changes using > that interface rather than by disabling the clocks. I've got devices > which can do glitch free updates of active clocks so having to disable > would be a real restriction, and cpufreq would have issues with actually > disabling the clock too I expect. > I agree that imposing a "disable clk before changing rate" policy in the framework core is a bad idea. During discussion on the CLK_GATE_SET_RATE flag in the patch #2 Shawn commented that he has some clks that must be enabled to change their rates (I assume he means PLLs but that detail doesn't really matter). Regards, Mike -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html