Messages in this thread | | | From | "Turquette, Mike" <> | Date | Tue, 20 Mar 2012 16:53:56 -0700 | Subject | Re: [PATCH v7 2/3] clk: introduce the common clock framework |
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On Tue, Mar 20, 2012 at 10:46 AM, Saravana Kannan <skannan@codeaurora.org> wrote: > On Tue, March 20, 2012 7:02 am, Shawn Guo wrote: >> On Thu, Mar 15, 2012 at 11:11:19PM -0700, Mike Turquette wrote: >> ... >>> +struct clk_ops { >>> + int (*prepare)(struct clk_hw *hw); >>> + void (*unprepare)(struct clk_hw *hw); >>> + int (*enable)(struct clk_hw *hw); >>> + void (*disable)(struct clk_hw *hw); >>> + int (*is_enabled)(struct clk_hw *hw); >>> + unsigned long (*recalc_rate)(struct clk_hw *hw, >>> + unsigned long parent_rate); >> >> I believe I have heard people love the interface with parent_rate >> passed in. I love that too. But I would like to ask the same thing >> on .round_rate and .set_rate as well for the same reason why we have >> it for .recalc_rate. > > In my case, for most clocks, set rate involves reparenting. So, what does > passing parent_rate for these even mean? Passing parent_rate seems more > apt for recalc_rate since it's called when the parent rate changes -- so, > the actual parent itself is not expected to change.
From my conversations with folks across many platforms, I think that the way your clock tree expects to change rates is the exception, not the rule. As such you should just ignore the parent_rate parameter as it useless to you.
> I could ignore the parameter, but just wondering how many of the others > see value in this. And if we do add this parameter, it shouldn't be made > mandatory for the platform driver to use it (due to other assumptions the > clock framework might make).
From my rough census of folks that actually need .set_rate support, I think that everyone except MSM could benefit from this. Your concept of clk_set_rate is everyone else's clk_set_parent.
Ignoring the new parameter should cause you no harm. It does make me wonder if it would be a good idea to pass in the parent rate for .set_parent, which is analogous to .set_rate in many ways.
Regards, Mike
> -Saravana -- 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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