[PATCH 1/1] ACPI: introduce kernel parameter acpi_sleep=sci_force_enable

[Chase Douglas]

On Thu, Apr 22, 2010 at 1:31 PM, Andy Whitcroft <apw at canonical.com> wrote:
> From: Zhang Rui <rui.zhang at intel.com>
>
> Introduce kernel parameter acpi_sleep=sci_force_enable
>
> some laptop requires SCI_EN being set directly on resume,
> or else they hung somewhere in the resume code path.
>
> We already have a blacklist for these laptops but we still need
> this option, especially when debugging some suspend/resume problems,
> in case there are systems that need this workaround and are not yet
> in the blacklist.
>
> Signed-off-by: Zhang Rui <rui.zhang at intel.com>
> Acked-by: Rafael J. Wysocki <rjw at sisk.pl>
> Signed-off-by: Len Brown <len.brown at intel.com>
>
> (cherry picked from commit d7f0eea9e431e1b8b0742a74db1a9490730b2a25 upstream)
> BugLink: http://bugs.launchpad.net/bugs/553498
>
> Signed-off-by: Andy Whitcroft <apw at canonical.com>
> ---
>  Documentation/kernel-parameters.txt |    5 ++++-
>  arch/x86/kernel/acpi/sleep.c        |    2 ++
>  drivers/acpi/sleep.c                |   29 +++++++++++++++++------------
>  include/linux/acpi.h                |    1 +
>  4 files changed, 24 insertions(+), 13 deletions(-)
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 345c399..5f6aa11 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -241,7 +241,7 @@ and is between 256 and 4096 characters. It is defined in the file
>
>        acpi_sleep=     [HW,ACPI] Sleep options
>                        Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
> -                                 old_ordering, s4_nonvs }
> +                                 old_ordering, s4_nonvs, sci_force_enable }
>                        See Documentation/power/video.txt for information on
>                        s3_bios and s3_mode.
>                        s3_beep is for debugging; it makes the PC's speaker beep
> @@ -254,6 +254,9 @@ and is between 256 and 4096 characters. It is defined in the file
>                        of _PTS is used by default).
>                        s4_nonvs prevents the kernel from saving/restoring the
>                        ACPI NVS memory during hibernation.
> +                       sci_force_enable causes the kernel to set SCI_EN directly
> +                       on resume from S1/S3 (which is against the ACPI spec,
> +                       but some broken systems don't work without it).
>
>        acpi_use_timer_override [HW,ACPI]
>                        Use timer override. For some broken Nvidia NF5 boards
> diff --git a/arch/x86/kernel/acpi/sleep.c b/arch/x86/kernel/acpi/sleep.c
> index ca93638..8b85734 100644
> --- a/arch/x86/kernel/acpi/sleep.c
> +++ b/arch/x86/kernel/acpi/sleep.c
> @@ -162,6 +162,8 @@ static int __init acpi_sleep_setup(char *str)
>  #endif
>                if (strncmp(str, "old_ordering", 12) == 0)
>                        acpi_old_suspend_ordering();
> +               if (strncmp(str, "sci_force_enable", 16) == 0)
> +                       acpi_set_sci_en_on_resume();
>                str = strchr(str, ',');
>                if (str != NULL)
>                        str += strspn(str, ", \t");
> diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c
> index cf3101f..22f4831 100644
> --- a/drivers/acpi/sleep.c
> +++ b/drivers/acpi/sleep.c
> @@ -81,6 +81,23 @@ static int acpi_sleep_prepare(u32 acpi_state)
>  #ifdef CONFIG_ACPI_SLEEP
>  static u32 acpi_target_sleep_state = ACPI_STATE_S0;
>  /*
> + * According to the ACPI specification the BIOS should make sure that ACPI is
> + * enabled and SCI_EN bit is set on wake-up from S1 - S3 sleep states.  Still,
> + * some BIOSes don't do that and therefore we use acpi_enable() to enable ACPI
> + * on such systems during resume.  Unfortunately that doesn't help in
> + * particularly pathological cases in which SCI_EN has to be set directly on
> + * resume, although the specification states very clearly that this flag is
> + * owned by the hardware.  The set_sci_en_on_resume variable will be set in such
> + * cases.
> + */
> +static bool set_sci_en_on_resume;
> +
> +void __init acpi_set_sci_en_on_resume(void)
> +{
> +       set_sci_en_on_resume = true;
> +}
> +
> +/*
>  * ACPI 1.0 wants us to execute _PTS before suspending devices, so we allow the
>  * user to request that behavior by using the 'acpi_old_suspend_ordering'
>  * kernel command line option that causes the following variable to be set.
> @@ -170,18 +187,6 @@ static void acpi_pm_end(void)
>  #endif /* CONFIG_ACPI_SLEEP */
>
>  #ifdef CONFIG_SUSPEND
> -/*
> - * According to the ACPI specification the BIOS should make sure that ACPI is
> - * enabled and SCI_EN bit is set on wake-up from S1 - S3 sleep states.  Still,
> - * some BIOSes don't do that and therefore we use acpi_enable() to enable ACPI
> - * on such systems during resume.  Unfortunately that doesn't help in
> - * particularly pathological cases in which SCI_EN has to be set directly on
> - * resume, although the specification states very clearly that this flag is
> - * owned by the hardware.  The set_sci_en_on_resume variable will be set in such
> - * cases.
> - */
> -static bool set_sci_en_on_resume;
> -
>  extern void do_suspend_lowlevel(void);
>
>  static u32 acpi_suspend_states[] = {
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index c010b94..07432a1 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -251,6 +251,7 @@ int acpi_check_mem_region(resource_size_t start, resource_size_t n,
>  void __init acpi_no_s4_hw_signature(void);
>  void __init acpi_old_suspend_ordering(void);
>  void __init acpi_s4_no_nvs(void);
> +void __init acpi_set_sci_en_on_resume(void);
>  #endif /* CONFIG_PM_SLEEP */
>
>  struct acpi_osc_context {
> --
> 1.7.0.4

This all looks reasonable to me, and gives us an easier way to debug
this issue when it crops up again.

Acked-by: Chase Douglas <chase.douglas at canonical.com>