APPLIED[bionic]: ACK/cmnt: [SRU] [Artful/linux-oem] [PATCH 1/1] ACPI / PM: Allow deeper wakeup power states with no _SxD nor _SxW

[Seth Forshee]

On Wed, Mar 28, 2018 at 11:58:16PM +0800, Kai-Heng Feng wrote:
> Stefan Bader <stefan.bader at canonical.com> wrote:
> 
> > On 28.03.2018 10:55, Kai-Heng Feng wrote:
> > > From: Daniel Drake <drake at endlessm.com>
> > > 
> > > BugLink: https://bugs.launchpad.net/bugs/1759511
> > > 
> > > acpi_dev_pm_get_state() is used to determine the range of allowable
> > > device power states when going into S3 suspend. This is implemented
> > > by executing the _S3D and _S3W ACPI methods.
> > > 
> > > Linux follows the ACPI spec behaviour in that when _S3D is implemented
> > > and _S3W is not, Linux will not go into a power state deeper than the one
> > > returned by _S3D for a wakeup-enabled device.
> > > 
> > > However, this same logic is being applied to the case when neither
> > > _S3D nor _S3W are present, and the result is that this function
> > > decides that the device must stay in D0 (fully on) state.
> > > 
> > > This is breaking USB wakeups on Asus V222GA and Acer XC-830. _S3D and
> > > _S3W are not present, so the USB controller is left in the D0 running
> > > state during S3, and hence it is unable to generate a PME# wake event.
> > > 
> > > The ACPI spec is unclear on which power states are permissable for
> > > wakeup-enabled devices when both _S3D and _S3W are missing.
> > > However, USB wakeups work fine on these platforms under Windows, where
> > > device manager shows that they are using D3 device state for the USB
> > > controller in S3.
> > > 
> > > I assume that the "max = min" clamping done by the code here is
> > > specifically written for the _S3D but no _S3W case. By making the
> > > code true to those conditions, avoiding them on these platforms,
> > > the controller will be put into D3 state and USB wakeups start working.
> > > 
> > > Additionally I feel that this change makes the code more directly
> > > mirror the wording of the ACPI spec and it's associated lack of clarity.
> > > 
> > > Thanks to Mathias Nyman for pointing us in the right direction.
> > > 
> > > Signed-off-by: Daniel Drake <drake at endlessm.com>
> > > Link: http://lkml.kernel.org/r/CAB4CAwf_k-WsF3zL4epm9TKAOu0h=Bv1XhXV_gY3bziOo_NPKA@mail.gmail.com
> > > 
> > > https://phabricator.endlessm.com/T21410
> > > Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki at intel.com>
> > > (cherry picked from commit bf8c6184e0c3d4d5e005e085e9f96f478a267b20
> > > git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git
> > > linux-next)
> > > Signed-off-by: Kai-Heng Feng <kai.heng.feng at canonical.com>
> > Acked-by: Stefan Bader <stefan.bader at canonical.com>
> > 
> > > ---
> > 
> > Since this is pulled from linux-next, I would suspect this is also
> > wanted in
> > Bionic, right?
> 
> This patch should be included for all linux version.
> I planed to ask linux-stable to include the patch once it's in Linus' tree,
> so we will get this patch through stable update.

We should go ahead and get it into bionic anyway. Applied to
bionic/master-next.