Re: [PATCH v2 2/5] clk: sunxi: Add USB clock register defintions

[Maxime Ripard <maxime.ripard-wi1+55ScJUtKEb57/3fJTNBPR1lH4CV8@public.gmane.org>]

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Hi Hans,

On Tue, Jan 28, 2014 at 11:00:45AM +0100, Hans de Goede wrote:
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> Hi,
> 
> On 01/28/2014 10:44 AM, Maxime Ripard wrote:
> > On Mon, Jan 27, 2014 at 03:54:14PM +0100, Hans de Goede wrote:
> >>>> "allwinner,sun5i-a13-usb-gates-clk" - for usb gates + resets on A13
> >>> 
> >>> Maybe we can just remove the gates from there? Even though they
> >>> are gates, they are also (a bit) more than that.
> >> 
> >> To be clear you mean s/usb-gates-clk/usb-clk/ right ?
> > 
> > Yep, exactly
> > 
> >>> I guess that means that we will have the OHCI0 gate declared
> >>> with <&...-gates-clk 6>, while it's actually the first gate for
> >>> this clock?
> >> 
> >> Correct.
> >> 
> >>> Maybe introducing an offset field in the gates_data would be a
> >>> good idea, so that we always start from indexing the gates from
> >>> 0 in the DT?
> >> 
> >> Well for the other "gates" type clks we also have holes in the
> >> range, and we always refer to the clk with the bit number in the
> >> reg as the clock-cell value.
> > 
> > Yes, we have holes, but I see two majors differences here: - the
> > other gates are just gates, while the usb clocks are a bit more
> > than that.
> 
> The usb-clk registers contain more then that, but the bits we are
> talking about now are gates.
> 
> > - the other gates' gating bits thus all start at bit 0, while
> > - here, since it's kind of a "mixed" clock, the gating bits start
> > - at bit 6 (on the A20 at least)
> 
> Right, still I believe that the consistent thing to do is keeping
> the bit-number for the bit in the register controlling the gate as
> the specifier.  When adding new dts entries / reviewing existing
> ones I'm used to matching the specifier to the bit-nr in the
> data-sheet, I think making things different just for this one
> register is counter productive.

And if you turn it the other way around, it would be inconsistent that
all gates indices start at 0, and we would start at 6 here :)

Plus, this clock is already a special case, since it's the only gate
that is more than just a gate so far.

Maxime

-- 
Maxime Ripard, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

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