linux-kernel - Re: [PATCH RFC RFT 3/3] clk: introduce CLK_ENABLE_HAND

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Date:	Tue, 11 Aug 2015 19:17:13 +0100
From:	Lee Jones <lee.jones@...aro.org>
To:	Michael Turquette <mturquette@...libre.com>
Cc:	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Maxime Coquelin <maxime.coquelin@...com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-clk@...r.kernel.org, Stephen Boyd <sboyd@...eaurora.org>,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	Sascha Hauer <s.hauer@...gutronix.de>
Subject: Re: [PATCH RFC RFT 3/3] clk: introduce CLK_ENABLE_HAND_OFF flag

On Tue, 11 Aug 2015, Michael Turquette wrote:

> Quoting Geert Uytterhoeven (2015-08-11 03:11:05)
> > Hi Maxime,
> > 
> > On Tue, Aug 11, 2015 at 12:02 PM, Maxime Coquelin
> > <maxime.coquelin@...com> wrote:
> > > How can we pass CLK_ENABLE_HAND_OFF flag to a specific clock on STi
> > > platform?
> > 
> > Add the flag to the relevant clocks in the C code, e.g. in
> > clk_register_flexgen():
> > 
> >         if (!strcmp(name, "clk-icn-cpu"))
> >                 init.flags |= CLK_ENABLE_HAND_OFF;
> > 
> > > Could we imagine having a kind of "clocks-enable-hand-off" property we could
> > > use in our clock controller DT node?
> > 
> > You can imagine doing "flex_flags |= CLK_ENABLE_HAND_OFF" in
> > st_of_flexgen_setup(), depending on the presence of such a property.
> 
> This is precisely what Lee is trying to avoid. The would constitute a
> hand-rolled, open-code, gather-and-mark exercise that drivers would have
> to re-invent each time. (rough paraphrase of what Lee said)

Thanks.

> I think that we can come up with a reasonable DT wrapper around the
> flag. I will be ecstatic if we can agree that the meaning of the flag
> can be tweaked just a bit to mean, "prevent this critical clock from
> being disabled, as it was enabled out of reset or by the bootloader,
> until a driver claims it and calls clk_prepare_enable".

Easy, how about:

'prevent_this_critical_clock_from_being_disabled_as_it_was_enabled_out_of_reset_or_by_the_bootloader_until_a_driver_claims_it_and_calls_clk_prepare_enable'

Or

I could come up with something else?

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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