* 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.
Thanks,
Ingo
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