On 4 September 2013 04:06, Tomasz Figa <tomasz.figa@xxxxxxxxx> wrote: > Hi Chander, > > On Tuesday 03 of September 2013 17:04:28 Chander Kashyap wrote: >> Some platform has provision to change cpu parent clock during >> cpu frequency scaling. This patch series provides a mechanism to >> implement the same using CCF. >> >> Patch1 provides mechanism to migrate to new parent temporarily. >> >> Patch2 updates the user of clk_register_mux and DEFINE_CLK_MUX which are >> modified to add support for clk migration. >> >> Patch3 adds support to Exynos5250 to use the clock parent migration >> feature implemented in CCF. > > I don't really like this approach. A need to change mux setting > temporarily is heavily platform-specific and I don't think it should be > handled by generic code. As of now beside samsung platforms, tegra is doing temporary parent migration. That why i opted to implement this feature in generic code. Here only set_parent operation is called on mux_clk. which is again implemented in generic framework. So i dont think any other platform specific requirements need to be taken care. >First of all there are many factor that you would > have to account for to make this solution generic, such as: > - board specific alternative parents, Yes true, that's why, that information is passed during registration time. > - exact moment of parent change, Here it is only during set rate operation. > - some other platform specific conditions, like CPU voltage that must be That will be handled separately when actual migration of cpufreq driver will be done. > changed when mux is changed, because it changes CPU frequency, > - and probably a lot of more factors that only people working with all > the platforms supported (and unsupported yet) by Linux. > > I can see at least two solutions for this problem that don't require > changing core code of common clock framework: > > 1) Implementing a special clock type using normal mux ops, but also > registering a notifier for its PRE_RATE_CHANGE and POST_RATE_CHANGE events > to perform parent switching. > > 2) Using normal mux clock, but registering such notifiers in clock > controller or cpufreq driver. > I agree with you, but i am attempting through generic framework be keeping in mind the future usage of this feature by other platforms. > Best regards, > Tomasz > -- with warm regards, Chander Kashyap -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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