Re: [PATCH] ACPI: introduce kernel parameter acpi_sleep=s3_set_sci_en

["Rafael J. Wysocki" <rjw@sisk.pl>]

On Tuesday 27 October 2009, Zhang Rui wrote:
> Introduce kernel parameter acpi_sleep=s3_set_sci_en
> 
> 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 lattops 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@intel.com>

I'm generally fine with this, but ...

> ---
>  Documentation/kernel-parameters.txt |    5 ++++-
>  arch/x86/kernel/acpi/sleep.c        |    4 ++++
>  drivers/acpi/sleep.c                |    6 ++++++
>  include/linux/acpi.h                |    3 +++
>  4 files changed, 17 insertions(+), 1 deletion(-)
> 
> Index: linux-2.6/drivers/acpi/sleep.c
> ===================================================================
> --- linux-2.6.orig/drivers/acpi/sleep.c
> +++ linux-2.6/drivers/acpi/sleep.c
> @@ -182,6 +182,12 @@ static void acpi_pm_end(void)
>   */
>  static bool set_sci_en_on_resume;
>  
> +void __init acpi_set_sci_en_on_resume(void)
> +{
> +	set_sci_en_on_resume = true;
> +	return 0;
> +}
> +
>  extern void do_suspend_lowlevel(void);
>  
>  static u32 acpi_suspend_states[] = {
> Index: linux-2.6/arch/x86/kernel/acpi/sleep.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/acpi/sleep.c
> +++ linux-2.6/arch/x86/kernel/acpi/sleep.c
> @@ -162,6 +162,10 @@ static int __init acpi_sleep_setup(char 
>  #endif
>  		if (strncmp(str, "old_ordering", 12) == 0)
>  			acpi_old_suspend_ordering();
> +#ifdef CONFIG_SUSPEND
> +		if (strncmp(str, "s3_set_sci_en", 13) == 0)
> +			acpi_set_sci_en_on_resume();
> +#endif /* CONFIG_SUSPEND */

... do we really need these #ifdefs?

>  		str = strchr(str, ',');
>  		if (str != NULL)
>  			str += strspn(str, ", \t");
> Index: linux-2.6/include/linux/acpi.h
> ===================================================================
> --- linux-2.6.orig/include/linux/acpi.h
> +++ linux-2.6/include/linux/acpi.h
> @@ -251,6 +251,9 @@ int acpi_check_mem_region(resource_size_
>  void __init acpi_no_s4_hw_signature(void);
>  void __init acpi_old_suspend_ordering(void);
>  void __init acpi_s4_no_nvs(void);
> +#ifdef CONFIG_SUSPEND
> +void __init acpi_set_sci_en_on_resume(void);
> +#endif /* CONFIG_SUSPEND*/

s4_no_nvs is hibernation-specific, but it's not under a #ifdef.

>  #endif /* CONFIG_PM_SLEEP */
>  
>  #define OSC_QUERY_TYPE			0
> Index: linux-2.6/Documentation/kernel-parameters.txt
> ===================================================================
> --- linux-2.6.orig/Documentation/kernel-parameters.txt
> +++ linux-2.6/Documentation/kernel-parameters.txt
> @@ -241,7 +241,7 @@ and is between 256 and 4096 characters. 
>  
>  	acpi_sleep=	[HW,ACPI] Sleep options
>  			Format: { s3_bios, s3_mode, s3_beep, s4_nohwsig,
> -				  old_ordering, s4_nonvs }
> +				  old_ordering, s4_nonvs, s3_set_sci_en }
>  			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. 
>  			of _PTS is used by default).
>  			s4_nonvs prevents the kernel from saving/restoring the
>  			ACPI NVS memory during hibernation.
> +			s3_set_sci_en causes the kernel to set SCI_EN directly
> +			on resume from S3 (which is against the ACPI specification,
> +			but some broken systems don't work without it).
>  
>  	acpi_use_timer_override [HW,ACPI]
>  			Use timer override. For some broken Nvidia NF5 boards

Thanks,
Rafael