On Friday, June 29, 2012, preeti wrote: > > From: Preeti U Murthy <preeti@xxxxxxxxxxxxxxxxxx> > > 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@xxxxxxxxxxxxxxxxxx> > Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> > Reviewed-by: Deepthi Dharwar <deepthi@xxxxxxxxxxxxxxxxxx> > Signed-off-by: Preeti U Murthy <preeti@xxxxxxxxxxxxxxxxxx> The patch didn't get any better as a result of modifying the changelog. Please consider it as rejected. Thanks, Rafael
