Clock and regulator frameworks have support for disabling unused clocks and
regulators at system init to save power when bootloaders leave them in a less
than desirable state. If no driver has requested for a clock/regulator to be
ON by the time kernel init reaches late_initcall level, they were considered
unused.
This worked well/good enough for compiled in drivers before deferred probe
was introduced. But with deferred probe, it's quite likely that devices that
match with compiled in drivers will continue to probe well past late_initcall
(at least as far as I can understand). So, we need to wait for deferred
probing during kernel init to complete before we do the disable of unused
clocks/regulators.
If there's a better or more obvious solution, I'm all ears. Another approach
would have been to add a "probe_done_initcall" level. But that seems overkill
and I don't think adding yet another initcall level is a great idea.
Thanks,
Saravana
Saravana Kannan (3):
driver core: Add API to wait for deferred probe to complete during
init
clk: Disable unused clocks after deferred probing is done
regulator: core: Disable unused regulators after deferred probing is
done
drivers/base/dd.c | 8 ++++++++
drivers/clk/clk.c | 4 +++-
drivers/regulator/core.c | 4 +++-
include/linux/device.h | 1 +
4 files changed, 15 insertions(+), 2 deletions(-)
--
1.7.8.3
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