LKML Archive on lore.kernel.org
help / color / mirror / Atom feed
From: "Li, Aubrey" <aubrey.li@linux.intel.com>
To: Ingo Molnar <mingo@kernel.org>,
	"alan@linux.intel.com" <alan@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@linux.intel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	arjan@linux.intel.com, "Rafael J. Wysocki" <rjw@rjwysocki.net>,
	Len.Brown@intel.com, x86@kernel.org,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] x86: Bypass legacy PIC and PIT on ACPI hardware reduced platform
Date: Wed, 04 Mar 2015 13:26:12 +0800	[thread overview]
Message-ID: <54F69774.2050400@linux.intel.com> (raw)
In-Reply-To: <20150304050858.GB5158@gmail.com>

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/
> 
> 


  reply	other threads:[~2015-03-04  5:26 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-04  3:23 Li, Aubrey
2015-03-04  5:08 ` Ingo Molnar
2015-03-04  5:26   ` Li, Aubrey [this message]
2015-03-04  5:31     ` Ingo Molnar
2015-03-04  6:04       ` Li, Aubrey
2015-03-04  7:37         ` Ingo Molnar
2015-03-04  8:43           ` Arjan van de Ven
2015-03-04  9:50             ` Borislav Petkov
2015-03-04 14:16               ` Rafael J. Wysocki
2015-03-04 14:05                 ` Borislav Petkov
2015-03-04 14:38                   ` Rafael J. Wysocki
2015-03-04 20:21                   ` Alan Cox
2015-03-04 21:52                     ` Rafael J. Wysocki
2015-03-05 11:26                       ` Li, Aubrey
2015-03-05 16:05                       ` Alan Cox
2015-03-04 14:36               ` Arjan van de Ven
2015-03-04 20:11                 ` Ingo Molnar
2015-03-05 11:13                   ` Li, Aubrey
2015-03-05 11:36                     ` Ingo Molnar
2015-03-05 12:42                       ` Li, Aubrey
2015-03-05 16:06                         ` Alan Cox
2015-03-09 23:26                         ` Li, Aubrey
2015-03-10  8:06                           ` Ingo Molnar
2015-03-11  4:14                             ` Li, Aubrey
2015-03-04 20:18               ` Alan Cox

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=54F69774.2050400@linux.intel.com \
    --to=aubrey.li@linux.intel.com \
    --cc=Len.Brown@intel.com \
    --cc=alan@linux.intel.com \
    --cc=arjan@linux.intel.com \
    --cc=hpa@linux.intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=mingo@redhat.com \
    --cc=rjw@rjwysocki.net \
    --cc=tglx@linutronix.de \
    --cc=x86@kernel.org \
    --subject='Re: [PATCH] x86: Bypass legacy PIC and PIT on ACPI hardware reduced platform' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).