Re: [RFC][RFT][PATCH] ACPI: Protection from suspending in the middle of EC transaction

[Alexey Starikovskiy <astarikovskiy@suse.de>]

Henrique de Moraes Holschuh пишет:
> On Sun, 31 Jan 2010, Maxim Levitsky wrote:
>> Unfortunately, this patch even causes regressions on my notebook (it
>> survive 63 hibernate cycles), but now I battery driver reports 'battery
>> absent', backlight driver reports 0 brightness, but reload helped.
> 
> ...
> 
>> I think that not only _PTS ans _WAK are problematic. What about other
>> ACPI drivers that start accessing the EC before it is resumed?
>> I think that these cause the problems I observe.
> 
> ACPI drivers might access the EC (even indirectly, through the DSDT).  And
> platform drivers do often access the EC both at suspend and resume time.
Actually, only SBS and thinkpad-acpi access EC directly. All others go through
DSDT for access. Still, stopping EC in .suspend is too early, IMHO...
> 
> This needs some sort of strong ordering, the EC must suspend last, and
> resume first (as seen by any ACPI and ACPI-aware drivers such as libata,
> some platform drivers, etc).  If EC interrupts are a problem, maybe it can
> be kicked to poll mode for the suspend/resume transition?
It's this way already for about a year now... The problem is that EC driver might be 
stopped in middle of the transaction, thus leaving EC in unknown state for BIOS or 
switch-over kernel.