Exynos4412-based Odroid boards (X2, U3, U3+) don't reset PMIC configuration during hardware reset. This causes serious issues with CPUfreq, when ARM voltage is set below 1.0V. When one resets the board when CPUfreq selected one of lower Exynos 4412 operating points (for example: 200MHz and 0.9V), the bootloader crashes and it is not possible to restart the board without turning power off.
This patch provides a workaround for this issue by increasing the start of valid range for vdd_arm regulator from 1.0V. After such change, CPUfreq can still use lower operating points, but the voltage won't be decreased below 1.0V and as a result it will be possible to reset board at any time. Signed-off-by: Marek Szyprowski <m.szyprow...@samsung.com> --- Hello, This issue was there from the beggining, but I was not able to reproduce it. It has been already reported by Tobias in early Feb 2015 (http://www.spinics.net/lists/linux-samsung-soc/msg42294.html). Recently, after CPUfreq changes (conversion to generic cpufreq dt and enabling cpufreq in exynos_defconfig) it was much easier to observe this issue. This workaround lets one still use CPUfreq and avoid unexpect board crashes during reboot (both 'standard' and emergency). Best regards Marek Szyprowski, PhD Samsung R&D Institute Poland --- arch/arm/boot/dts/exynos4412-odroid-common.dtsi | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/boot/dts/exynos4412-odroid-common.dtsi b/arch/arm/boot/dts/exynos4412-odroid-common.dtsi index db52841..fca8233 100644 --- a/arch/arm/boot/dts/exynos4412-odroid-common.dtsi +++ b/arch/arm/boot/dts/exynos4412-odroid-common.dtsi @@ -370,7 +370,7 @@ buck2_reg: BUCK2 { regulator-name = "vdd_arm"; - regulator-min-microvolt = <900000>; + regulator-min-microvolt = <1000000>; regulator-max-microvolt = <1350000>; regulator-always-on; regulator-boot-on; -- 1.9.2 -- To unsubscribe from this list: send the line "unsubscribe linux-samsung-soc" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
