Hi, On Tuesday, September 01, 2015 10:57:37 PM Krzysztof Kozlowski wrote: > 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. This work-around is needed also for the old exynos-cpufreq driver as the problem was already there on some Odroid setups (please read the mail from February pointed by Marek for details). We don't have a better fix for the time being so I think that it should be merged now regardless of cpufreq-dt changes status. > Anyway for the time being: > Reviewed-by: Krzysztof Kozlowski <k.kozlowski@xxxxxxxxxxx> > > Thanks Marek, > BR Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics -- 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
 |