Re: [PATCH 08/11] macintosh/via-pmu: Replace via-pmu68k driver with via-pmu driver

[Geert Uytterhoeven]

Hi Finn,

On Wed, Jun 6, 2018 at 8:57 AM, Finn Thain <fthain@xxxxxxxxxxxxxxxxxxx> wrote:
> On Mon, 4 Jun 2018, Geert Uytterhoeven wrote:
>> > Don't call pmu_shutdown() or pmu_restart() on early PowerBooks: the
>> > PMU device found in these PowerBooks isn't supported.
>>
>> Shouldn't that be a separate patch?
>>
>> > --- a/arch/m68k/mac/misc.c
>> > +++ b/arch/m68k/mac/misc.c
>>
>> > @@ -477,9 +445,8 @@ void mac_poweroff(void)
>> >                    macintosh_config->adb_type == MAC_ADB_CUDA) {
>> >                 cuda_shutdown();
>> >  #endif
>> > -#ifdef CONFIG_ADB_PMU68K
>> > -       } else if (macintosh_config->adb_type == MAC_ADB_PB1
>> > -               || macintosh_config->adb_type == MAC_ADB_PB2) {
>> > +#ifdef CONFIG_ADB_PMU
>> > +       } else if (macintosh_config->adb_type == MAC_ADB_PB2) {
>> >                 pmu_shutdown();
>> >  #endif
>> >         }
>> > @@ -519,9 +486,8 @@ void mac_reset(void)
>> >                    macintosh_config->adb_type == MAC_ADB_CUDA) {
>> >                 cuda_restart();
>> >  #endif
>> > -#ifdef CONFIG_ADB_PMU68K
>> > -       } else if (macintosh_config->adb_type == MAC_ADB_PB1
>> > -               || macintosh_config->adb_type == MAC_ADB_PB2) {
>> > +#ifdef CONFIG_ADB_PMU
>> > +       } else if (macintosh_config->adb_type == MAC_ADB_PB2) {
>> >                 pmu_restart();
>> >  #endif
>> >         } else if (CPU_IS_030) {
>>
>
> The stability problem here is bigger than just pmu_restart() and
> pmu_shutdown(), so those hunks are insufficient. You need to prevent the
> via-pmu68k driver from loading in the first place and to drop all the
> PMU_68K_V1 cases.
>
> But splitting this patch in that way creates potential merge conflicts,
> which is a hassle. E.g. this hunk:
>
> -       ....
> -       switch (macintosh_config->adb_type) {
> -       case MAC_ADB_PB1:
> -               pmu_kind = PMU_68K_V1;
> -               break;
> -       case MAC_ADB_PB2:
> -               pmu_kind = PMU_68K_V2;
> -               break;
> -       default:
> -               pmu_kind = PMU_UNKNOWN;
> -               return -ENODEV;
> -       }
> -       ...
>
> would get split over two patches.
>
> The way I see it, having no PMU driver for PMU_68K_V1 machines is a bug.
> And loading any of the existing PMU drivers on that hardware is also a
> bug. These bugs are equivalent in that either one means you can't use the
> keyboard, trackpad etc. So there's no value in cherry-picking the other
> bug.
>
> If you are using v4.17 on a PMU_68K_V1 machine, you probably already have
> CONFIG_ADB_PMU68K=n. With that config, here's nothing to be gained from
> bisecting these changes.
>
> Does that make sense? Did I overlook other possible reason(s) to split up
> this patch?

So 4.17 mac_defconfig won't work on PMU_68K_V1 machines?
Perhaps that should be fixed first.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds