Messages in this thread | | | Date | Fri, 12 Mar 2010 09:46:02 +0100 | Subject | Re: [PATCH 05/11] ST SPEAr: Added clock framework for SPEAr platform and machines | From | Linus Walleij <> |
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2010/3/11 Shiraz HASHIM <shiraz.hashim@st.com>: > On 3/11/2010 12:30 PM, Linus Walleij wrote: >> 2010/3/3 Viresh KUMAR <viresh.kumar@st.com>: >> (...) >>> + if (unlikely(clk->flags & RESET_TO_ENABLE)) >>> + val &= ~(1 << clk->en_reg_bit); >>> + else >>> + val |= 1 << clk->en_reg_bit; >>> + writel(val, clk->en_reg); >> >> I don't understand one bit of this. (...) > > The intention to use RESET_TO_ENABLE flag is to generalize clock > enable/disable across platforms.
I misread the entire thing, there was some bad parsing inside my head... Sorry about this.
>> OMAP uses CPUfreq but that is really about the CPU. As it happens, all >> their clk:s always change frequency at the same operating points as the >> CPU. So they can have pre/post calls from CPUfreq in their code, but >> this will not work with things like PrimeCells where other users of the cell >> may not have operating points correlated with CPU operating points. >> >> (I'm not requesting you to solve this problem, more to be aware of it.) > > I think generally in embedded systems (at least in our case :) ) the CPU clock > itself is not completly independent. It is generally tied with some system > clock, which has an impact on bus and peripheral clocks. In that sense cpu freq > would be a better mean to notify frequency change. > In any case, clock framework don't intend to do it. It only need to reflect > correct system state. Is this understanding correct?
Currently it's like that but I think clk really needs a frequency change notification mechanism. I will have to deal with it some day I think :-/
Yours, Linus Walleij -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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