2015-09-01 22:08 GMT+09:00 Marek Szyprowski <m.szyprowski@xxxxxxxxxxx>: > 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 s/crashes/hangs/ ? I did not observe a crash but a silent hang. > 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.szyprowski@xxxxxxxxxxx> Do you plan to send the same fix for Trats2 board? Everything above applies there as well plus suspend is affected. The board cannot properly resume. > --- > 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). Work-around looks nice and clean. It still allows to use cpufreq and reduce the energy consumption. The patch should go along with cpufreq-dt support for Exynos4412 which hopefully would be for v4.3. If cpufreq-dt for Exynos4412 won't get to v4.3 we can figure out proper solution, not a work-around. Anyway for the time being: Reviewed-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx> Thanks Marek, BR > > 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 majordomo@xxxxxxxxxxxxxxx > More majordomo info at http://vger.kernel.org/majordomo-info.html -- 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
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