On Tue, 17 Jun 2014, Mike Turquette wrote: > Quoting Paul Walmsley (2014-06-17 01:15:09) > > On Tue, 17 Jun 2014, Tomi Valkeinen wrote: > > > > > When setting the rate of a clock, by default the clock framework will > > > change the parent of the clock to the most suitable one in > > > __clk_mux_determine_rate() (most suitable by looking at the clock rate). > > > > That is just insane. > > The patch description is insane. The framework has nothing to do with > this dynamic re-parenting behavior and certainly the framework does not > force this behavior on clock providers. This behavior is specific to > users of __clk_mux_determine_rate. drivers/clk/clk-mux.c and drivers/clk/clk.c aren't considered part of the clock framework? > Those are: > > 1) drivers/clk/clk-mux.c > 2) drivers/clk/qcom/mmcc-msm8960.c > 3) drivers/clk/samsung/clk-s3c2410-dclk.c > 4) drivers/clk/ti/mux.c > > If dynamic re-parenting by default doesn't work for your platform then > you have two choices: > > 1) use the CLK_SET_RATE_NO_REPARENT flag (as this patch does) > 2) don't use the basic divider type and write your own > > If you choose #2 then all you have to do when implementing > .determine_rate is ignore the best_parent_rate argument. > > Finally when the .determine_rate callback was introduced (allowing > dynamic re-parenting from a call to clk_set_rate) the > CLK_SET_RATE_NO_REPARENT flag was applied to all affected users to > maintain prior behavior and prevent regressions. I don't disagree that some platforms might want this behavior. But it's not a safe default, the flag should be the other way around. Rare is the software engineer that knows whether the clock muxes on their platform are glitchless. - Paul -- 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
