[PATCH 0/4] clk: Provide option to unprepare unused clocks at late init

[mturquette@linaro.org (Mike Turquette)]

Quoting Ulf Hansson (2013-01-24 08:45:52)
> From: Ulf Hansson <ulf.hansson@linaro.org>
> 
> The disable_unused sequence executed at late init, is already handling the
> fast unused ungated clocks to be gated. This patchset extends this sequence to
> include the slow unused prepared clocks to be unprepared.
> 
> The default behavior will not change in this patchset. To unprepare unused
> clocks during the disable_unused sequence, the clk_hw needs to implement
> the new optional callback, is_prepared.
> 
> The motivation for this patchset is to save power. Clocks that is from
> bootloaders prepared|enabled, but not used should be unprepared|disabled.
> 
> Patch 4 is specific for ux500, which implements the is_prepared callback
> for it's PRMCU clocks.
> 
> Note that patch 1-3 has been sent earlier, but since a proof of concept
> patch could be useful, as patch 4 is, the hole patchset is resent.
> 

Hi Ulf,

I had some minor discussion in patch #1.  Otherwise patches #2 & #3 look
good to me.

Patch #4 is a bit interesting.  There is nothing wrong with it per se,
but the general layering of the prcmu power stuff is the opposite of how
I had envisioned things.  Your .prepare callback is making calls to some
pm_qos api but a quick grep did not reveal any definitions for those
functions, just some stubs in include/linux/mfd/dbx500-prcmu.h.

Do these functions scale voltage?  I had figured that some day
per-device pm qos apis would call the clk api, not the other way around.

Anyways that is just food for thought and no reason to block patch #4.

Regards,
Mike

> Ulf Hansson (4):
>   clk: Introduce optional is_prepared callback
>   clk: Unprepare the unused prepared slow clocks at late init
>   clk: Introduce optional unprepare_unused callback
>   clk: ux500: Support is_prepared callback for clk-prcmu
> 
>  drivers/clk/clk.c             |   53 ++++++++++++++++
>  drivers/clk/ux500/clk-prcmu.c |  134 ++++++++++++++++++++++++-----------------
>  include/linux/clk-provider.h  |   11 ++++
>  3 files changed, 144 insertions(+), 54 deletions(-)
> 
> -- 
> 1.7.10