* Li, Aubrey <aubrey...@linux.intel.com> wrote:
> On 2015/3/4 13:31, Ingo Molnar wrote:
> >
> > * Li, Aubrey <aubrey...@linux.intel.com> wrote:
> >
> >> On 2015/3/4 13:08, Ingo Molnar wrote:
> >>>
> >>> * Li, Aubrey <aubrey...@linux.intel.com> wrote:
> >>>
> >>>> On ACPI hardware reduced platform, the legacy PIC and PIT may not be
> >>>> initialized even though they may be present in silicon. Touching
> >>>> these legacy components causes unexpected result on system.
> >>>>
> >>>> On Bay Trail-T(ASUS-T100) platform, touching these legacy components
> >>>> blocks platform hardware low idle power state(S0ix) during system
> >>>> suspend.
> >>>> So we should bypass them on ACPI hardware reduced platform.
> >>>>
> >>>> Suggested-by: Arjan van de Ven <ar...@linux.intel.com>
> >>>> Signed-off-by: Li Aubrey <aubrey...@linux.intel.com>
> >>>> Cc: Len Brown <len.br...@intel.com>
> >>>> Cc: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
> >>>> ---
> >>>> arch/x86/kernel/irqinit.c | 6 +++++-
> >>>> arch/x86/kernel/time.c | 3 ++-
> >>>> 2 files changed, 7 insertions(+), 2 deletions(-)
> >>>>
> >>>> diff --git a/arch/x86/kernel/irqinit.c b/arch/x86/kernel/irqinit.c
> >>>> index 70e181e..9a64cc3 100644
> >>>> --- a/arch/x86/kernel/irqinit.c
> >>>> +++ b/arch/x86/kernel/irqinit.c
> >>>> @@ -75,7 +75,11 @@ void __init init_ISA_irqs(void)
> >>>> #if defined(CONFIG_X86_64) || defined(CONFIG_X86_LOCAL_APIC)
> >>>> init_bsp_APIC();
> >>>> #endif
> >>>> - legacy_pic->init(0);
> >>>> + if (acpi_gbl_reduced_hardware) {
> >>>> + pr_info("Using NULL legacy PIC\n");
> >>>> + legacy_pic = &null_legacy_pic;
> >>>> + } else
> >>>> + legacy_pic->init(0);
> >>>>
> >>>> for (i = 0; i < nr_legacy_irqs(); i++)
> >>>> irq_set_chip_and_handler(i, chip, handle_level_irq);
> >>>> diff --git a/arch/x86/kernel/time.c b/arch/x86/kernel/time.c
> >>>> index 25adc0e..5ba94fa 100644
> >>>> --- a/arch/x86/kernel/time.c
> >>>> +++ b/arch/x86/kernel/time.c
> >>>> @@ -14,6 +14,7 @@
> >>>> #include <linux/i8253.h>
> >>>> #include <linux/time.h>
> >>>> #include <linux/export.h>
> >>>> +#include <linux/acpi.h>
> >>>>
> >>>> #include <asm/vsyscall.h>
> >>>> #include <asm/x86_init.h>
> >>>> @@ -76,7 +77,7 @@ void __init setup_default_timer_irq(void)
> >>>> /* Default timer init function */
> >>>> void __init hpet_time_init(void)
> >>>> {
> >>>> - if (!hpet_enable())
> >>>> + if (!hpet_enable() && !acpi_gbl_reduced_hardware)
> >>>> setup_pit_timer();
> >>>> setup_default_timer_irq();
> >>>> }
> >>>
> >>> So the whole acpi_gbl_reduced_hardware flaggery sucks as it mixes
> >>> various hardware drivers that have little relation to each other...
> >>>
> >>> Instead of having a proper platform init this flag hooks into various
> >>> drivers and generic code, such as the efi reboot and shutdown code,
> >>> and now the generic irq init code.
> >>>
> >>> For this IRQ init problem, why not add a proper callback to
> >>> x86_platform_ops, define your own IRQ init function, initialize it in
> >>> your platform init sequence and let it be called? That solves it
> >>> without creating an ugly mix of different platform methods.
> >>>
> >>> For the EFI shutdown case, what's wrong with setting your own
> >>> pm_power_off handler like most of the other platforms are doing? Plus
> >>> the EFI code in drivers/firmware/efi/reboot.c should probably only set
> >>> the shutdown handler if pm_power_off is still NULL.
> >>
> >> I think our goal is to make the code as generic as possible for all
> >> x86 platform, rather than creating a new x86 branch, I added Alan
> >> Cox for this strategy discussion.
> >>
> >> Do you have any inputs for the patch itself?
> >
> > Other than that the patch is unacceptable for an upstream merge in its
> > current form for the reason I mentioned? No.
>
> So you are suggesting we extend a new x86 platform branch and
> override the x86_platform and pm_power_off and reboot, like what
> intel_mid does?
Well, what I suggested above was to add an IRQ init method to
x86_platform (and make use of it on your platform), and to
use the existing pm_power_off method for the reboot quirk.
Using 'acpi_gbl_reduced_hardware' flag outside the ACPI code
is a mistake.
Thanks,
Ingo
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