Messages in this thread | | | Date | Wed, 04 Mar 2015 13:26:12 +0800 | From | "Li, Aubrey" <> | Subject | Re: [PATCH] x86: Bypass legacy PIC and PIT on ACPI hardware reduced platform |
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On 2015/3/4 13:08, Ingo Molnar wrote: > > * Li, Aubrey <aubrey.li@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 <arjan@linux.intel.com> >> Signed-off-by: Li Aubrey <aubrey.li@linux.intel.com> >> Cc: Len Brown <len.brown@intel.com> >> Cc: Rafael J. Wysocki <rafael.j.wysocki@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?
Thanks, -Aubrey
> > Thanks, > > Ingo > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > >
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