On Tue, Aug 20, 2019 at 12:05:01PM -0700, Rajat Jain wrote: > On Tue, Aug 20, 2019 at 3:34 AM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > On Thu, May 23, 2019 at 10:05:35PM +0200, Heiner Kallweit wrote: > > > Background of this extension is a problem with the r8169 network driver. > > > Several combinations of board chipsets and network chip versions have > > > problems if ASPM is enabled, therefore we have to disable ASPM per default. > > > However especially on notebooks ASPM can provide significant power-saving, > > > therefore we want to give users the option to enable ASPM. With the new sysfs > > > attribute users can control which ASPM link-states are enabled/disabled. > > > > > > Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx> > > > --- > > > Documentation/ABI/testing/sysfs-bus-pci | 13 ++ > > > drivers/pci/pci.h | 8 +- > > > drivers/pci/pcie/aspm.c | 180 +++++++++++++++++++++++- > > > 3 files changed, 193 insertions(+), 8 deletions(-) > > > > > > diff --git a/Documentation/ABI/testing/sysfs-bus-pci b/Documentation/ABI/testing/sysfs-bus-pci > > > index 8bfee557e..38fe358de 100644 > > > --- a/Documentation/ABI/testing/sysfs-bus-pci > > > +++ b/Documentation/ABI/testing/sysfs-bus-pci > > > @@ -347,3 +347,16 @@ Description: > > > If the device has any Peer-to-Peer memory registered, this > > > file contains a '1' if the memory has been published for > > > use outside the driver that owns the device. > > > + > > > +What: /sys/bus/pci/devices/.../power/aspm_link_states > > > +Date: May 2019 > > > +Contact: Heiner Kallweit <hkallweit1@xxxxxxxxx> > > > +Description: > > > + If ASPM is supported for an endpoint, then this file can be > > > + used to enable / disable link states. A link state > > > + displayed in brackets is enabled, otherwise it's disabled. > > > + To control link states (case insensitive): > > > + +state : enables a supported state > > > + -state : disables a state > > > + none : disables all link states > > > + all : enables all supported link states > > > > IIUC this "aspm_link_states" file will contain things like this: > > > > L0S L1 L1.1 L1.2 # All states supported, all disabled > > [L0S] L1 # L0s enabled, L1 supported but disabled > > [L0S] [L1] # L0s and L1 enabled > > ... > > > > and the control is by writing things like this to it: > > > > +L1 # enables L1 > > +L1.1 # enables L1.1 > > -L0S # disables L0s > > > > I know this file structure is similar to protocol handling in > > drivers/media/rc/rc-main.c, but Documentation/filesystems/sysfs.txt > > suggests single values in a file, and Greg recently pointed out that > > we screwed up some PCI AER stats [1]. > > > > So I'm thinking maybe we should split this into several files, e.g., > > > > /sys/devices/pci*/.../power/aspm_l0s > > /sys/devices/pci*/.../power/aspm_l1 > > /sys/devices/pci*/.../power/aspm_l1.1 > > /sys/devices/pci*/.../power/aspm_l1.2 > > > > which would contain just 1/0 values, and we'd write 1/0 to > > enable/disable things. > > > > Since the L1 PM Substates control register has separate enable bits > > for PCI-PM L1.1 and L1.2, we might also want a way to manage those. > > > > Bjorn > > > > [1] https://lore.kernel.org/r/20190621072911.GA21600@xxxxxxxxx > > Sorry, this has been sitting on my plate for some time now. I'll work > on it and send out a patch later in this week. Don't worry, I cc'd you mostly as FYI because you're a recent contributor to aspm.c in this area, though I wouldn't complain about AER stats sysfs patches either :) Bjorn
