[PATCH 1/2 V3] clk: sirf: add CSR atlas7 clk and reset support

Stephen Boyd sboyd at codeaurora.org
Thu May 21 14:33:24 PDT 2015

On 05/16, Barry Song wrote:
> 2015-05-16 2:30 GMT+08:00 Stephen Boyd <sboyd at codeaurora.org>:
> > On 05/15, Barry Song wrote:
> >> From: Zhiwu Song <Zhiwu.Song at csr.com>
> >>
> >> the hardware node includes both clock and reset support, so it
> >> is named as "car".
> >> this patch implements Flexible clocks(mux, divider, gate), Selectable
> >> clock(mux, divider, gate), root clock(gate),leaf clock(gate), others.
> >> it also implements the reset controller functionality.
> >>
> >> Signed-off-by: Zhiwu Song <Zhiwu.Song at csr.com>
> >> Signed-off-by: Guo Zeng <Guo.Zeng at csr.com>
> >> Signed-off-by: Barry Song <Baohua.Song at csr.com>
> >> ---
> >

Yes this has already been applied, but replying to the last

> >> +
> >> +
> >> +CLK_OF_DECLARE(atlas7_clk, "sirf,atlas7-car", atlas7_clk_init);
> >>
> >
> > I'm also curious if we actually need to use CLK_OF_DECLARE here
> > or if could we use a platform device.
> >
> > Even if we need to use CLK_OF_DECLARE because some timer or other
> > early device needs a clock, I wonder if we shouldn't also make
> > these things into real platform drivers that register the other
> > clocks that aren't necessary for the early boot process.
> >
> it seems it is a general question not only for this driver?

Yes it is.

> the main difficulty is maintaining the boot sequence of the platform
> devices and other machine codes which require clocks. it seems it is
> the easiest way to make clk ready earlier than other drivers.
> and i don't think registering these clocks takes much boot time and
> make boot slower at least for atlas7 platform since there is no sleep
> and long delay in the procedure.

It isn't really about making boot time faster, it's about using
the proper linux device model for clock providers. That way when
we want to support things like suspend/resume, deferred probe,
devm_*(), sysfs, etc. we can use the device model instead of
resorting to things like syscore_ops for suspend/resume or
forgoing features entirely.

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