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

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Message-ID: <55C9DE57.2090105@st.com>
Date:	Tue, 11 Aug 2015 13:36:55 +0200
From:	Maxime Coquelin <maxime.coquelin@...com>
To:	Geert Uytterhoeven <geert@...ux-m68k.org>
CC:	Lee Jones <lee.jones@...aro.org>,
	Michael Turquette <mturquette@...libre.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

Hi Geert,

On 08/11/2015 12:11 PM, Geert Uytterhoeven wrote:
> 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;
The main problem I see with this proposal
>
>> 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.
Exactly, this is what I was thinking about.

>
> However, not disabling clocks is a software policy, not a hardware description,
> so IMHO it doesn't belong in DT.
>
I disagree here because if these clocks get gated the system is dead, so 
I wouldn't call this a SW Policy.
Moreover, I don't see how this property is different from 
assigned-clock-parents and assigned-clock-rates properties, which have 
been accepted.

Thanks,
Maxime
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