RE: 2.6.16-rc5: known regressions [TP 600X S3, vanilla DSDT]

["Yu, Luming" <luming.yu@intel.com>]

>> So, please try hack thermal.c by removing calls to _TMP.
>
>I did something like that before, by changing acpi_evaluate_integer()
>to return 3000 if it is asked for _TMP.  
>
>--- a/utils.c	2006-03-15 01:42:34.000000000 -0500
>+++ b/utils.c	2006-03-14 23:36:59.000000000 -0500
>@@ -270,7 +270,15 @@ acpi_evaluate_integer(acpi_handle handle
> 	memset(element, 0, sizeof(union acpi_object));
> 	buffer.length = sizeof(union acpi_object);
> 	buffer.pointer = element;
>-	status = acpi_evaluate_object(handle, pathname, 
>arguments, &buffer);
>+	if (strcmp(pathname, "_TMP") != 0)
>+	  status = acpi_evaluate_object(handle, pathname, 
>arguments, &buffer);
>+	else {
>+	  printk(KERN_INFO PREFIX "acpi_evaluate_integer: 
>Faking _TMP\n");
>+	  status = AE_OK;
>+	  element->type = ACPI_TYPE_INTEGER;
>+	  element->integer.value = 3000; /* 27 C, in deciKelvins */
>+	}
>+
> 	if (ACPI_FAILURE(status)) {
> 		acpi_util_eval_error(handle, pathname, status);
> 		return_ACPI_STATUS(status);
>
>
>The alternative, obvious change in thermal.c (diff below) turns out
>not to be a minimal change.  If acpi_thermal_get_temperature() returns
>with a failure, then most of the later methods in THM0 aren't
>executed, so one is actually commenting out much more than _TMP.
>
>Which is why I think the minimal change is the diff above to utils.c.
>With that change the system never hung.

Good, this is exactly what I wanted.  How many times you tested with
this
hack without hang?  If s3 hang really goes away , then probably you can
move on , and come up with a real patch that could go into the 2.6.16. 
What do you think? :-)

The short-term proper way could be:
1. add a global variable: acpi_in_suspend.
2. in acpi_pm_prepare:
	a.call acpi_os_wait_events_complete()
	b.set acpi_in_suspend = YES.
   in acpi_pm_finish :
	set acpi_in_suspend = NO.
3. in acpi_thermal_run:
	if (acpi_in_suspend == YES)
		do nothing.

The long-term proper way should be:
1. ACPI subsystem should stop invoking BIOS before Suspend except
for several necessary AML methods that are required to put 
the platform into S3 state.  Otherwise, un-tested BIOS code path 
could cause trouble to linux, because I assume such platform 
should have been tested under windows. 

Thanks,
Luming
 
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