Re: [PATCH RFC RFT 3/3] clk: introduce CLK_ENABLE_HAND_OFF flag
From: Michael Turquette
Date: Tue Aug 11 2015 - 13:09:49 EST
Quoting Geert Uytterhoeven (2015-08-11 03:11:05)
> Hi Maxime,
> On Tue, Aug 11, 2015 at 12:02 PM, Maxime Coquelin
> <maxime.coquelin@xxxxxx> 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
> 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)
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".
Then everyone should be happy.
> However, not disabling clocks is a software policy, not a hardware description,
> so IMHO it doesn't belong in DT.
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
> -- Linus Torvalds
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