On 22/05/14 13:44, Tushar Behera wrote: > On 22 May 2014 16:04, Tomasz Figa <t.f...@samsung.com> wrote: >> On 22.05.2014 07:13, Tushar Behera wrote: >>> On 05/20/2014 10:13 PM, Tomasz Figa wrote: >>>> This patch introduces a driver that handles configuration of CLKOUT pin >>>> of Exynos SoCs that can be used to output certain clocks from inside of >>>> the SoC to a dedicated output pin. >>>> >>>> Signed-off-by: Tomasz Figa <t.f...@samsung.com> >>>> --- >>>> .../devicetree/bindings/arm/samsung/pmu.txt | 30 ++++ >>>> drivers/clk/samsung/Makefile | 1 + >>>> drivers/clk/samsung/clk-exynos-clkout.c | 153 >>>> +++++++++++++++++++++ >>>> 3 files changed, 184 insertions(+) >>>> create mode 100644 drivers/clk/samsung/clk-exynos-clkout.c >>>> >>> >>> [ ... ] >>> >>>> + clkout->clk_table[0] = clk_register_composite(NULL, "clkout", >>>> + parent_names, parent_count, &clkout->mux.hw, >>>> + &clk_mux_ops, NULL, NULL, &clkout->gate.hw, >>>> + &clk_gate_ops, CLK_SET_RATE_PARENT >>>> + | CLK_SET_RATE_NO_REPARENT); >>> >>> Would you please remove CLK_SET_RATE_NO_REPARENT flag from here? Let me >>> know if you have reservations against this. >> >> The problem with clock reparenting is that there are certain parent >> clocks of CLKOUT, rate of which changes at runtime, e.g. clocks derived >> from APLL or bus clocks, which can be reconfigured by cpufreq or devfreq. >> > > +CC: Sylwester Nawrocki > > Okay. But in cases where there is only 1 valid parent clock provided > through DT (at the moment for Exynos5250/Exynos5420), would it be safe > to set that clock as the parent of CLKOUT? Otherwise, this clock is > not usable ATM.
I'd prefer to not allow re-parenting here, as it will not work in all system configurations and seems not reliable in general. >>> With RFC patches, I am able to do a clk_set_rate() on this clock to >>> get a 24MHz output to the codec clock. With this flag set, I again have >>> to rely on the default value set to this register in bootloader. >>> >> >> This problem should be handled by initializing clocks from DT. I'm not >> sure why it hasn't been implemented yet... > > I would be happy to get it done that way. I can see a patch from > Sylwester regarding this, but there hasn't been a conclusion as of > yet. > > https://lkml.org/lkml/2014/4/9/173 I posted a next version recently [1], any feedback on that is welcome. I used these patches for the camera on Trats2 and the audio on Odroid U3 clocks configuration. [1] http://www.spinics.net/lists/devicetree/msg34718.html -- Thanks, Sylwester -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
