Re: [Xen-devel] [PATCH v4 3/5] acpi: Adjust linux acpi OS functions to new extended parameter

[Ben Guthro <Benjamin.Guthro@xxxxxxxxxx>]

On 06/27/2013 11:59 AM, Moore, Robert wrote:
> I have not seen a discussion of the details on this, so can someone explain 
> to me just why acpi_os_prepare_sleep is needed, what does it do, and why 
> these changes are being made to ACPICA code?

Hi Bob,

I'm not familiar with your background here, so I apologize if I am stating 
obvious things below.

acpi_os_prepare_sleep() has been in the acpica code for some time now, allowing 
for OS specific hooks to account for differences between OS architectures.

Specifically, it has been in since:

commit 09f98a825a821f7a3f1b162f9ed023f37213a63b
Author: Tang Liang <liang.tang@xxxxxxxxxx>
Date:   Fri Dec 9 10:05:54 2011 +0800

    x86, acpi, tboot: Have a ACPI os prepare sleep instead of calling 
tboot_sleep.
    
    The ACPI suspend path makes a call to tboot_sleep right before
    it writes the PM1A, PM1B values. We replace the direct call to
    tboot via an registration callback similar to __acpi_register_gsi.
    
    CC: Len Brown <len.brown@xxxxxxxxx>
    Acked-by: Joseph Cihula <joseph.cihula@xxxxxxxxx>
    Acked-by: Rafael J. Wysocki <rjw@xxxxxxx>
    [v1: Added __attribute__ ((unused))]
    [v2: Introduced a wrapper instead of changing tboot_sleep return values]
    [v3: Added return value AE_CTRL_SKIP for acpi_os_sleep_prepare]
    Signed-off-by: Tang Liang <liang.tang@xxxxxxxxxx>
    [v1: Fix compile issues on IA64 and PPC64]
    [v2: Fix where __acpi_os_prepare_sleep==NULL and did not go in sleep 
properly]
    Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>



In this case, the Xen hypervisor, and not linux needs to actually put the 
system into S3, so this hook gives the architecture to do so.

This change does not introduce this functionality, but simply moves the code 
around into the proper locations, such that the acpica code no longer need to 
include linux specific headers.

I hope this helps.
If you have specific questions, please let me know.

Regards,
Ben

> 
> Thanks,
> Bob
> 
> 
>> -----Original Message-----
>> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
>> Sent: Thursday, June 27, 2013 8:12 AM
>> To: Ben Guthro
>> Cc: Moore, Robert; xen-devel@xxxxxxxxxxxxx; Konrad Rzeszutek Wilk; Rafaell
>> J . Wysocki; linux-acpi@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx
>> Subject: Re: [PATCH v4 3/5] acpi: Adjust linux acpi OS functions to new
>> extended parameter
>>
>>>>> On 27.06.13 at 17:02, Ben Guthro <benjamin.guthro@xxxxxxxxxx> wrote:
>>> Change the function definitions of acpi_os_prepare_sleep() and
>>> acpi_os_set_prepare_sleep() to pass along the new extended sleep
>>> parameter.
>>>
>>> Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
>>> Signed-off-by: Ben Guthro <benjamin.guthro@xxxxxxxxxx>
>>> Cc: Bob Moore <robert.moore@xxxxxxxxx>
>>> Cc: Rafaell J. Wysocki <rjw@xxxxxxx>
>>> Cc: linux-acpi@xxxxxxxxxxxxxxx
>>> ---
>>>   drivers/acpi/osl.c   |   16 ++++++++--------
>>>   include/linux/acpi.h |    6 +++---
>>>   2 files changed, 11 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/drivers/acpi/osl.c b/drivers/acpi/osl.c index
>>> e721863..0251c9b 100644
>>> --- a/drivers/acpi/osl.c
>>> +++ b/drivers/acpi/osl.c
>>> @@ -77,8 +77,8 @@ EXPORT_SYMBOL(acpi_in_debugger);  extern char
>>> line_buf[80];
>>>   #endif                            /*ENABLE_DEBUGGER */
>>>
>>> -static int (*__acpi_os_prepare_sleep)(u8 sleep_state, u32 pm1a_ctrl,
>>> -                                 u32 pm1b_ctrl);
>>> +static int (*__acpi_os_prepare_sleep)(u8 sleep_state, u32 val_a, u32
>> val_b,
>>> +                                 bool extended);
>>
>> So from here till patch 5 the build will be half broken because of the
>> type mismatches? I think at least the types of the consumers need to be
>> changed in this patch; leaving the meat of the Xen change to patch 4 is
>> perhaps fine.
>>
>> Jan
>>
>>>
>>>   static acpi_osd_handler acpi_irq_handler;  static void
>>> *acpi_irq_context; @@ -1757,13 +1757,13 @@ acpi_status
>>> acpi_os_terminate(void)
>>>     return AE_OK;
>>>   }
>>>
>>> -acpi_status acpi_os_prepare_sleep(u8 sleep_state, u32 pm1a_control,
>>> -                             u32 pm1b_control)
>>> +acpi_status acpi_os_prepare_sleep(u8 sleep_state, u32 val_a, u32 val_b,
>>> +                             u8 extended)
>>>   {
>>>     int rc = 0;
>>>     if (__acpi_os_prepare_sleep)
>>> -           rc = __acpi_os_prepare_sleep(sleep_state,
>>> -                                        pm1a_control, pm1b_control);
>>> +           rc = __acpi_os_prepare_sleep(sleep_state, val_a, val_b,
>>> +                                        extended);
>>>     if (rc < 0)
>>>             return AE_ERROR;
>>>     else if (rc > 0)
>>> @@ -1772,8 +1772,8 @@ acpi_status acpi_os_prepare_sleep(u8
>>> sleep_state, u32 pm1a_control,
>>>     return AE_OK;
>>>   }
>>>
>>> -void acpi_os_set_prepare_sleep(int (*func)(u8 sleep_state,
>>> -                          u32 pm1a_ctrl, u32 pm1b_ctrl))
>>> +void acpi_os_set_prepare_sleep(int (*func)(u8 sleep_state, u32 val_a,
>>> +                          u32 val_b, bool extended))
>>>   {
>>>     __acpi_os_prepare_sleep = func;
>>>   }
>>> diff --git a/include/linux/acpi.h b/include/linux/acpi.h index
>>> 709a2f2..26f9996 100644
>>> --- a/include/linux/acpi.h
>>> +++ b/include/linux/acpi.h
>>> @@ -477,8 +477,8 @@ static inline bool acpi_driver_match_device(struct
>>> device *dev,
>>>   #endif    /* !CONFIG_ACPI */
>>>
>>>   #ifdef CONFIG_ACPI
>>> -void acpi_os_set_prepare_sleep(int (*func)(u8 sleep_state,
>>> -                          u32 pm1a_ctrl,  u32 pm1b_ctrl));
>>> +void acpi_os_set_prepare_sleep(int (*func)(u8 sleep_state, u32 val_a,
>>> +                          u32 val_b, bool extended));
>>>   #ifdef CONFIG_X86
>>>   void arch_reserve_mem_area(acpi_physical_address addr, size_t size);
>>> #else @@ -488,7 +488,7 @@ static inline void
>>> arch_reserve_mem_area(acpi_physical_address addr,  }  #endif /*
>>> CONFIG_X86 */  #else -#define acpi_os_set_prepare_sleep(func,
>>> pm1a_ctrl, pm1b_ctrl) do { } while
>>> (0)
>>> +#define acpi_os_set_prepare_sleep(func, val_a, val_b, ext) do { }
>>> +while (0)
>>>   #endif
>>>
>>>   #if defined(CONFIG_ACPI) && defined(CONFIG_PM_RUNTIME)
>>> --
>>> 1.7.9.5
>>
>>
> 

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