[PATCH] ARM: multi_v7_defconfig: major refresh

Jon Medhurst (Tixy)
2014-08-01T15:53:19Z

On Fri, 2014-08-01 at 15:57 +0100, Sudeep Holla wrote:
>
> On 01/08/14 12:28, Jon Medhurst (Tixy) wrote:
> > On Fri, 2014-08-01 at 12:12 +0100, Sudeep Holla wrote:
> >>
> >> On 01/08/14 12:03, Olof Johansson wrote:
> >>> On Fri, Aug 1, 2014 at 4:01 AM, Jon Medhurst (Tixy) <tixy@linaro.org> wrote:
> >>>> On Fri, 2014-08-01 at 11:26 +0100, Sudeep Holla wrote:
>
> [...]
>
> >>>>
> >>>>> One way to achieve this:
> >>>>> (There's sysfs to re-enable it runtime)
> >>>>
> >>>> The opposite is also true, if you don't want the switcher enabled you
> >>>> can disable it by the same method after boot ;-)
> >>>>
> >>>>> -->8
> >>>>> diff --git a/arch/arm/common/bL_switcher.c b/arch/arm/common/bL_switcher.c
> >>>>> index 490f3dced749..f4c36e70166a 100644
> >>>>> --- a/arch/arm/common/bL_switcher.c
> >>>>> +++ b/arch/arm/common/bL_switcher.c
> >>>>> @@ -794,7 +794,7 @@ static int bL_switcher_hotplug_callback(struct
> >>>>> notifier_block *nfb,
> >>>>> return NOTIFY_DONE;
> >>>>> }
> >>>>>
> >>>>> -static bool no_bL_switcher;
> >>>>> +static bool no_bL_switcher = true;
> >>>>
> >>>> This changes the default for everyone, which I guess is fair enough if
> >>>> there is a good reason, but I'm not sure there is.
> >>>
> >>> No, I don't think there is.
> >>>
> >>
> >> It's just that people using TC2 will suddenly see 3 of the 5 CPUs missing.
> >
> > Yes, if they we're previously using multi_v7_defconfig (do people
> > working specifically with TC2's use that?)
> >
>
> I don't, but assumed many might use it.
>
> > Conversely, with the change in default proposed above, anyone with their
> > own configs enabling the switcher will suddenly see the number of CPUs
> > go from 2 to 5. We also have the situation where we have a config
> > option, which when enabled, doesn't actually do anything unless the user
> > also changes boot arguments or takes measures to enable it after boot.
> > Which seems the wrong way for things to work to me.
> >
>
> OK, makes sense. Just curious how many big.LITTLE platforms have CPUFreq
> support and integrated with bL switcher. Otherwise we end up switching
> clusters/cpus using dummy i/f anyways

Hmm, that is a point, there are 3 other big.LITTLE SoC's I can spot in
mainline [1], and I wouldn't want to speculate how they would be
affected by having the big.LITTLE switcher enabled.

[1] exynos5420, exynos5260, r8a7790

--
Tixy