Hi Mike, On Tue, Nov 13, 2012 at 2:52 AM, Mike Turquette <mturque...@ti.com> wrote: > Quoting Shiraz Hashim (2012-11-06 22:36:10) >> On Wed, Nov 7, 2012 at 11:42 AM, Shiraz Hashim >> <shiraz.linux.ker...@gmail.com> wrote: >> > Hi Mike, Rob, >> > >> > Devices in a SoC can have multiple possible clock sources which is >> > perfectly captured through clk framework. >> > >> > But the device itself may not be aware of the complex hierarchy above it. >> > In this case how do you suggest a board (through DT) should select its >> > preference. >> > >> > Is there some work already going on in this direction ? >> >> Just to make it clear, I already have referred the clock DT bindings and >> Shawn Guo patch on removing clk look up registration from kernel code. >> >> Here I am talking about possibility of selecting desired clock hierarchy >> by the boards about which device nodes are not aware. >> > > One way to achieve this is to use clk_set_rate as a way to switch > parents at run-time. The OMAP CCF code currently does this when > relocking PLLs and makes use of __clk_reparent to update the clock > framework's representation of the hierarchy dynamically. > > Maybe something like the following is helpful to you: > http://git.linaro.org/gitweb?p=people/mturquette/linux.git;a=blob;f=arch/arm/mach-omap2/dpll3xxx.c;h=f72dedb4eee892ce4cd5bdf22cc8c22510f3d526;hb=clk-omap-3.8#l542
Thanks for the information. So the generic SoC part can be handled through set_rate but what about boards preferences and restrictions. For e.g., it prefers to route a clock from a particular clk source only and wants its own fixed (as per its design) clk source selections. -- regards Shiraz Hashim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
