On Mon, Jun 15, 2020 at 12:43:15PM +0200, Marek Szyprowski wrote: > Add a simple custom voltage regulator coupler for Exynos5800 SoCs, which > require coupling between "vdd_arm" and "vdd_int" regulators. This coupler > ensures that the voltage values don't go below the bootloader-selected > operation point during the boot process until a the clients sets their > constraints. It is achieved by assuming minimal voltage value equal to > the current value if no constraints are set. This also ensures proper > voltage balancing if any of the client driver is missing. > > The balancing code comes from the regulator/core.c with the additional > logic for handling regulators without client constraints applied added. > > Reviewed-by: Dmitry Osipenko <digetx@xxxxxxxxx> > Signed-off-by: Marek Szyprowski <m.szyprowski@xxxxxxxxxxx> > --- > This patch is yet another attempt to fix the regulator coupling on > Exynos5800/5422 SoCs. Here are links to the previous attempts and > discussions: > > https://lore.kernel.org/linux-samsung-soc/20191008101709.qVNy8eijBi0LynOteWFMnTg4GUwKG599n6OyYoX1Abs@z/ > https://lore.kernel.org/lkml/20191017102758.8104-1-m.szyprowski@xxxxxxxxxxx/ > https://lore.kernel.org/linux-pm/cover.1589528491.git.viresh.kumar@xxxxxxxxxx/ > https://lore.kernel.org/linux-pm/20200528131130.17984-1-m.szyprowski@xxxxxxxxxxx/ > https://lore.kernel.org/linux-samsung-soc/57cf3a15-5d9b-7636-4c69-60742e8cfae6@xxxxxxxxxxx/ > https://lore.kernel.org/lkml/20200605063724.9030-1-m.szyprowski@xxxxxxxxxxx/ > > The problem is with "vdd_int" regulator coupled with "vdd_arm" on Odroid > XU3/XU4 boards family. "vdd_arm" is handled by CPUfreq. "vdd_int" is > handled by devfreq. CPUfreq initialized quite early during boot and it > starts changing OPPs and "vdd_arm" value. Sometimes CPU activity during > boot goes down and some low-frequency OPPs are selected, what in turn > causes lowering "vdd_arm". This happens before devfreq applies its > requirements on "vdd_int". Regulator balancing code reduces "vdd_arm" > voltage value, what in turn causes lowering "vdd_int" value to the lowest > possible value. This is much below the operation point of the wcore bus, > which still runs at the highest frequency. > > The issue was hard to notice because in the most cases the board managed > to boot properly, even when the regulator was set to lowest value allowed > by the regulator constraints. However, it caused some random issues, > which can be observed as "Unhandled prefetch abort" or low USB stability. > > Handling this case in the generic code has been rejected, so the only way > to ensure the desired behavior on Exynos5800-based SoCs is to make a > custom regulator coupler driver. I've tried hard to extract some common > code to simplify the exynos-regulator-coupler driver as much as possible, > but the difference between it and the generic code is so deep that this > approach failed, so indead I simply copied and modified the balancing > code. > > Best regards > Marek Szyprowski > --- > arch/arm/mach-exynos/Kconfig | 1 + > drivers/soc/samsung/Kconfig | 3 + > drivers/soc/samsung/Makefile | 1 + > .../soc/samsung/exynos-regulator-coupler.c | 221 ++++++++++++++++++ > 4 files changed, 226 insertions(+) > create mode 100644 drivers/soc/samsung/exynos-regulator-coupler.c > > diff --git a/arch/arm/mach-exynos/Kconfig b/arch/arm/mach-exynos/Kconfig > index 76838255b5fa..f185cd3d4c62 100644 > --- a/arch/arm/mach-exynos/Kconfig > +++ b/arch/arm/mach-exynos/Kconfig > @@ -118,6 +118,7 @@ config SOC_EXYNOS5800 > bool "Samsung EXYNOS5800" > default y > depends on SOC_EXYNOS5420 > + select EXYNOS_REGULATOR_COUPLER > > config EXYNOS_MCPM > bool > diff --git a/drivers/soc/samsung/Kconfig b/drivers/soc/samsung/Kconfig > index 19c4d3f1437b..5d7819b52eed 100644 > --- a/drivers/soc/samsung/Kconfig > +++ b/drivers/soc/samsung/Kconfig > @@ -43,4 +43,7 @@ config EXYNOS_PM_DOMAINS > bool "Exynos PM domains" if COMPILE_TEST > depends on PM_GENERIC_DOMAINS || COMPILE_TEST > > +config EXYNOS_REGULATOR_COUPLER > + bool "Exynos SoC Regulator Coupler" if COMPILE_TEST > + depends on ARCH_EXYNOS || COMPILE_TEST > endif > diff --git a/drivers/soc/samsung/Makefile b/drivers/soc/samsung/Makefile > index 31db65cb7aa3..93285faec416 100644 > --- a/drivers/soc/samsung/Makefile > +++ b/drivers/soc/samsung/Makefile > @@ -10,3 +10,4 @@ obj-$(CONFIG_EXYNOS_PMU_ARM_DRIVERS) += exynos3250-pmu.o exynos4-pmu.o \ > exynos5250-pmu.o exynos5420-pmu.o > obj-$(CONFIG_EXYNOS_PMU_ARM64_DRIVERS) += exynos-pm.o exynos5433-pmu.o You based this patch on some different tree. Does not apply. Best regards, Krzysztof > obj-$(CONFIG_EXYNOS_PM_DOMAINS) += pm_domains.o > +obj-$(CONFIG_EXYNOS_REGULATOR_COUPLER) += exynos-regulator-coupler.o
