Hi Michael,
On 2017-09-08 02:59, Michael Turquette wrote:
Hi Marek,
Quoting Marek Szyprowski (2017-08-21 01:04:58)
Dear All,
This patchset adds runtime PM support to common clock framework. This is an
attempt to implement support for clock controllers, which belongs to a power
domain. This approach works surprisingly well on Exynos 5433 SoC, what allowed
us to solve various freeze/crash issues related to power management.
The main idea behind this patchset is to keep clock's controller power domain
enabled every time when at least one of its clock is enabled or access to its
registers is being made. Clock controller driver (clock provider) can
supply a struct device pointer, which is the used by clock core for tracking and
managing clock's controller runtime pm state. Each clk_prepare() operation will
first call pm_runtime_get_sync() on the supplied device, while clk_unprepare()
will do pm_runtime_put() at the end.
This runtime PM feature has been tested with Exynos4412 (not included in this
patchset) and Exynos5433 clocks drivers. Both have some clocks, which belongs to
respective power domains and need special handling during power on/off
procedures. Till now it wasn't handled at all, what caused various problems.
Patches for clocks drivers change the way the clock provider is initialized.
Instead of CLK_OF_DECLARE based initialization, a complete platform device driver
infrastructure is being used. This is needed to let driver to use runtime PM
feature and integrate with generic power domains. The side-effect of this change
is a delay in clock provider registeration during system boot, so early
initialized drivers might get EPROBEDEFER error when requesting their clocks.
This was an issue for IOMMU drivers, but IOMMU deferred probe support has been
finally merged to v4.13-rc1 and now it is handled correctly.
Patches are based and tested on v4.13-rc5, but applies fine also on v4.13-rc1.
Patches look good to me. It's too late for the v4.14 PR, but I'll merge
this to clk-next after -rc1 drops.
Thanks! There will be a plenty of time to test them in linux-next then! :)
Best regards
--
Marek Szyprowski, PhD
Samsung R&D Institute Poland
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