Re: [PATCH] clk: Add functions to get optional clocks

From: Geert Uytterhoeven
Date: Wed Jul 18 2018 - 09:19:36 EST


Hi Russell,

On Wed, Jul 18, 2018 at 3:02 PM Russell King - ARM Linux
<linux@xxxxxxxxxxxxxxx> wrote:
> On Wed, Jul 18, 2018 at 01:57:38PM +0100, Phil Edworthy wrote:
> > Behaves the same as (devm_)clk_get except where there is no clock
> > producer. In this case, instead of returning -ENOENT, the function
> > returns NULL. This makes error checking simpler and allows
> > clk_prepare_enable, etc to be called on the returned reference
> > without additional checks.
>
> How does this work with non-DT systems, where looking a clock up which
> isn't yet registered with clkdev returns -ENOENT ?
>
> (clkdev doesn't know when all clocks are registered with it.)

Good question.

I guess all drivers trying to handle optional clocks this way are already broken
on non-DT systems where clocks may be registered late...

Gr{oetje,eeting}s,

Geert

--
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