Messages in this thread | | | Date | Wed, 31 Jan 2007 11:17:10 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH 09/23] clocksource: add block notifier |
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* Daniel Walker <dwalker@mvista.com> wrote:
> Adds a call back interface for register/rating change events. This is > also used later in this series to signal other interesting events.
This patch adds:
> +#define CLOCKSOURCE_NOTIFY_REGISTER 1 > +#define CLOCKSOURCE_NOTIFY_RATING 2 > +#define CLOCKSOURCE_NOTIFY_FREQ 4
and a later patch adds:
> +#define CLOCKSOURCE_NOTIFY_UNSTABLE 8
while i tentatively agree with the introduction of clocksource driver notifications in general (given any actual real users of that infrastructure), i can see three problems with your notifier changes:
firstly, with the full changes applied, CLOCKSOURCE_NOTIFY_RATING is totally unused (and not even driven by the core clocksource code).
secondly, CLOCKSOURCE_NOTIFY_REGISTER is only used by the core clocksource code and no register-notifier interface is exposed: this makes the whole thing an expensive NOP.
thirdly, CLOCKSOURCE_NOTIFY_FREQ is totally unused as well.
(there are tons of examples in the kernel of how to do driver notification APIs properly.)
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