Dear All, On 2016-10-24 14:12, Marek Szyprowski wrote:
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 4412 and 5433 SoCs, 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 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 exynos 4412 and 5433 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 is an issue for IOMMU drivers, so this patchset will be fully functional once the deferred probe for IOMMU will be merged. The side-effect of this patchset is the one can finally read /sys/kernel/debug/clk/clk_summary on all Exynos4412 boards without any freeze. If one wants to test this patchset (on Exynos4412 Trats2 device with FIMC-IS driver), I've provided a branch with all needed patches (fixes for Exynos, FIMC-IS driver and IOMMU deferred probe): https://git.linaro.org/people/marek.szyprowski/linux-srpol.git v4.9-clocks-pm-v3 Patches are based on vanilla v4.9-rc1 kernel.
If one want to test this patchset together with my recently posted Exynos IOMMU runtime PM patches (V5: http://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1253432.html),
I prepared a single branch with both patchsets and all their prerequisites: https://git.linaro.org/people/marek.szyprowski/linux-srpol.git v4.9-iommu-pm-v5-clocks-pm-v3 Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
