[PATCH V2 17/17] ARM: exynos: config: Enable cpuidle

[Bartlomiej Zolnierkiewicz]

On Monday, April 07, 2014 11:43:47 AM Daniel Lezcano wrote:
> On 04/04/2014 06:09 PM, Bartlomiej Zolnierkiewicz wrote:
> >
> > On Friday, April 04, 2014 03:43:09 PM Daniel Lezcano wrote:
> >> The cpuidle driver is broken since v3.11 and now we are at v3.14.
> >>
> >> Default the cpuidle driver to favorize a better detection next time.
> >>
> >> Signed-off-by: Daniel Lezcano <daniel.lezcano at linaro.org>
> >> Reviewed-by: Viresh Kumar <viresh.kumar at linaro.org>
> >> ---
> >>   arch/arm/configs/exynos_defconfig |    1 +
> >>   1 file changed, 1 insertion(+)
> >>
> >> diff --git a/arch/arm/configs/exynos_defconfig b/arch/arm/configs/exynos_defconfig
> >> index 4ce7b70..6ed4b34 100644
> >> --- a/arch/arm/configs/exynos_defconfig
> >> +++ b/arch/arm/configs/exynos_defconfig
> >> @@ -132,3 +132,4 @@ CONFIG_DEBUG_INFO=y
> >>   CONFIG_DEBUG_USER=y
> >>   CONFIG_CRYPTO_SHA256=y
> >>   CONFIG_CRC_CCITT=y
> >> +CONFIG_CPU_IDLE=y
> >
> > Sorry but I have to NAK this change.  There are three issues with AFTR
> > mode that should be resolved first before this patch can be merged:
> >
> > * The upstream Exynos cpuidle code lacks support for secure firmware and
> >    it is used on i.e. Trats2 boards (Exynos4412).  Attempts to use AFTR on
> >    such hardware results in oops + lockup.
> >    I have patches adding secure firmware support to Exynos cpuidle driver
> >    but they depend on Tomasz Figa's PM changes which are not yet upstream.
> 
> Ok.
> 
> > * Somebody needs to verify that the current Exynos cpuidle driver works
> >    in the AFTR mode on Exynos5420 for which support has been added recently
> >    (I really doubt it looking at some internal trees).
> 
> Rajeshwari (cc'ed) is working on creating a big.Little driver for this 
> board, so it will be a separate cpuidle driver.
> 
> > * Some of our u-boot bootloader versions are incompatible with AFTR.  We
> >    have observed the problem happening on Trats board (Exynos4210) on which
> >    it can be fixed by using the upstream u-boot version and Universal C210
> >    board (Exynos4210 with broken SMP support) on which there is no upstream
> >    u-boot available (IIRC) and because of the broken SMP support enabling
> >    cpuidle results in attempt to enter AFTR during boot + immediate lockup.
> >
> >    I know that this is mainly our problem but the issue is widespread on
> >    our targets and I believe that adding some workaround for it in cpuidle
> >    core would be beneficial for the whole cpuidle subsystem.  Namely there
> >    should be some way of telling cpuidle subsystem to either disable
> >    particular state(s) or limit the max available state.  I think that this
> >    can be also useful for testing and development of other cpuidle drivers.
> >
> > For now please change this patch to add CONFIG_CPU_IDLE=n instead (since
> > the config option is "default y" it will be auto-enabled if there is no
> > entry in the defconfig)..
> 
> Ok.
> 
> Kukjin, is it possible you merge patches 1->16 ?

It is OK given that patch #17 is fixed and merged at the same time
(preferably it should go before patches #1-16 to preserve bisectability).
Alternatively 'default y' should be removed from patch #16 before
the merge.  We really don't want to have EXYNOS cpuidle driver enabled
by default yet.

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics