[PATCH v9 4/6] ARM: Exynos: switch to using generic cpufreq driver for Exynos4210/5250/5420

Sjoerd Simons sjoerd.simons at collabora.co.uk
Mon Aug 25 01:11:37 PDT 2014


On Fri, 2014-08-22 at 16:54 -0700, Kevin Hilman wrote:
> Tomasz Figa <tomasz.figa at gmail.com> writes:
> > Kukjin,
> >
> > On 31.07.2014 20:32, Kukjin Kim wrote:
> >> On 07/30/14 17:07, Thomas Abraham wrote:
> >>> The new CPU clock type allows the use of generic CPUfreq drivers. So for
> >>> Exynos4210/5250, switch to using generic cpufreq driver. For Exynos5420,
> >>> which did not have CPUfreq driver support, enable the use of generic
> >>> CPUfreq driver.
> >>>
> >>> Suggested-by: Tomasz Figa<t.figa at samsung.com>
> >>> Cc: Kukjin Kim<kgene.kim at samsung.com>
> >> 
> >> Looks good to me,
> >> 
> >> Acked-by: Kukjin Kim <kgene.kim at samsung.com>
> >> 
> >> BTW, who will handle this series? I hope see this series in 3.17.
> >
> > This series consists mostly of clock changes and it likely depends on
> > patches already in my for-next, so I would be inclined toward taking it
> > through samsung-clk tree. 
> So has this series been picked up anywhere?  I don't see it in your
> samsung-clk tree, nor in Kukjin's for-next.
> Also, I'm curious whether or how this is has been tested on big.LITTLE
> SoCs.  
> I'm trying it on the 5800/Chromebook2 and it's not terribly stable.  I'm
> testing along with CPUidle, so there may be some untested interactions
> there as it seems a bit more stable without CPUidle enabled.
> I'd love to hear from anyone else that's testing CPUidle and CPUfreq
> together big.LITTLE 5420/5800, with or without the switcher.
> Also, the patch below[2] is needed for 5800.

For reference, I had the same patch in a kernel tree we recently used
for a demo on the chromebook 2 13" (Exynos 5800). We didn't see any
stability issues due to this without CPUidle (using the ondemand
govenor). The kernel we ended up using had CONFIG_BL_SWITCHER disabled,
but i don't remember seeing stability issues when i did a testrun with
that enabled.  

Sjoerd Simons <sjoerd.simons at collabora.co.uk>
Collabora Ltd.
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