Re: [PATCH] Cpuidle drivers, Suspend : Fix suspend/resume hang with intel_idle driver

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

On Friday, June 29, 2012, preeti wrote:
> 
> From: Preeti U Murthy <preeti@linux.vnet.ibm.com>
> 
> Dave Hansen reported problems with suspend/resume when used
> with intel_idle driver.More such problems were noticed.
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/674075.
> 
> The reason for this could not be suspected till he reported
> resume hang issue when used with acpi idle driver on his Lenovo-S10-3
> Atom netbook.
> 
> The patch-[PM / ACPI: Fix suspend/resume regression caused by cpuidle
> cleanup],fixed this issue by ensuring that acpi idle drivers prevent
> cpus from going into deeper sleep states during suspend to prevent
> resume hang on certain bios.
> http://marc.info/?l=linux-pm&m=133958534231884&w=2
> 
> Commit b04e7bdb984e3b7f62fb7f44146a529f88cc7639
> (ACPI: disable lower idle C-states across suspend/resume) throws
> light on the resume hang issue on certain specific bios.
> 
> Also the following lines in drivers/idle/intel_idle.c suggest intel_idle
> drivers should also ensure cpus are prevented from entering idle states
> during suspend to avoid a resume hang.
> 
> /*
>  * Known limitations
>  * [..]
>  *
>  * ACPI has a .suspend hack to turn off deep c-states during suspend
>  * to avoid complications with the lapic timer workaround.
>  * Have not seen issues with suspend, but may need same workaround here.
>  *
>  */
> This patch aims at having this fix in a place common to both the idle
> drivers.
> 
> Suspend is enabled only if ACPI is active on x86.Thus the setting of
> acpi_idle_suspend during suspend is moved up to ACPI specific code with
> both acpi and intel idle drivers checking if it is valid to enter deeper
> idle states.The setting of acpi_idle_suspend is done via PM_SUSPEND_PREPARE
> notifiers to avoid race conditions between processors entering idle states
> and the ongoing process of suspend.
> 
> The check on acpi_idle_suspend is included in the most appropriate header
> so as to be visible to both the idle drivers irrespective of the
> different configurations.Even if ACPI is disabled intel idle drivers can
> still carry out the acpi_idle_suspend check.
> 
> Reported-by: Dave Hansen <dave@linux.vnet.ibm.com>
> Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
> Reviewed-by: Deepthi Dharwar <deepthi@linux.vnet.ibm.com>
> Signed-off-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>

The patch didn't get any better as a result of modifying the changelog.

Please consider it as rejected.

Thanks,
Rafael