On Tue, Mar 10, 2015 at 3:55 PM, Sascha Hauer s.hauer@pengutronix.de wrote:
On Tue, Mar 10, 2015 at 09:53:19AM +0800, Pi-Cheng Chen wrote:
On 5 March 2015 at 15:42, Sascha Hauer s.hauer@pengutronix.de wrote:
My suggestion is to take another approach. Implement clk_set_rate for these muxes and in the set_rate hook:
- switch mux to intermediate PLL parent
- call clk_set_rate() for the real parent PLL
- switch mux back to real parent PLL
Hi Sascha,
Thanks for your suggestion. I've tried to take this approach, but there's some issues here.
Calling clk_set_rate() inside the set_rate callback of cpumux will cause an infinite recursive calling in the clock framework: mux.set_rate() -> pll.set_rate() -> mux.set_rate -> ...
I don't understand why setting the PLL rate should call into the mux set_rate. Are you sure you call clk_set_rate for the mux parent clk? I think the general approach should work, drivers/clk/sirf/clk-common.c does something similar in cpu_clk_set_rate(). If you like you can send me your work in progress state privatly, I'll have a look then.
Thanks for pointing me out the reference. I think I misunderstood the way you suggested to do it. I'll post the new version once the design including cpufreq part is finalized.
Best Regards, Pi-Cheng
I've also tries to update pll register settings in the set_rate() callback of cpumux, but the PLL clock information will not be correctly updated in this case.
No, that won't work.
Sascha
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