On Thu, Nov 21, 2019 at 01:03:06PM -0800, Rajat Jain wrote: > Hi, > > On Thu, Nov 21, 2019 at 12:49 PM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote: > > > > [+cc Rafael, Mika, Wong, Hui, Rajat, Keith, LKML, original patch at [5]] > > > > On Sat, Oct 05, 2019 at 02:07:56PM +0200, Heiner Kallweit wrote: > > > > > +What: /sys/bus/pci/devices/.../link_pm/clkpm > > > + /sys/bus/pci/devices/.../link_pm/l0s_aspm > > > + /sys/bus/pci/devices/.../link_pm/l1_aspm > > > + /sys/bus/pci/devices/.../link_pm/l1_1_aspm > > > + /sys/bus/pci/devices/.../link_pm/l1_2_aspm > > > + /sys/bus/pci/devices/.../link_pm/l1_1_pcipm > > > + /sys/bus/pci/devices/.../link_pm/l1_2_pcipm > > > +Date: October 2019 > > > +Contact: Heiner Kallweit <hkallweit1@xxxxxxxxx> > > > +Description: If ASPM is supported for an endpoint, then these files > > > + can be used to disable or enable the individual > > > + power management states. Write y/1/on to enable, > > > + n/0/off to disable. > > > > This is queued up for the v5.5 merge window, so if we want to tweak > > anything (path names or otherwise), now is the time. > > > > I think I might be inclined to change the directory from "link_pm" to > > "link", e.g., > > > > - /sys/bus/pci/devices/0000:00:1c.0/link_pm/clkpm > > + /sys/bus/pci/devices/0000:00:1c.0/link/clkpm > > > > because there are other things that haven't been merged yet that could > > go in link/ as well: > > > > * Mika's "link disable" control [1] > > * Dilip's link width/speed controls [2,3] > > > > The max_link_speed, max_link_width, current_link_speed, > > current_link_width files could also logically be in link/, although > > they've already been merged at the top level. > > > > Rajat's AER statistics change [4] is also coming. Those stats aren't > > link-related, so they wouldn't go in link/. The current strawman is > > an "aer_stats" directory, but I wonder if we should make a more > > generic directory like "errors" that could be used for both AER and > > DPC and potentially other error-related things. > > Sorry, I haven't been able to find time for it for some time. I doubt > if I'll be able to make it to 5.6 timeframe. Nevertheless... > > > > > For example, we could have these link-related things: > > > > /sys/.../0000:00:1c.0/link/clkpm # RW ASPM stuff > > /sys/.../0000:00:1c.0/link/l0s_aspm > > /sys/.../0000:00:1c.0/link/... > > /sys/.../0000:00:1c.0/link/disable # RW Mika > > /sys/.../0000:00:1c.0/link/speed # RW Dilip's control > > /sys/.../0000:00:1c.0/link/width # RW Dilip's control > > /sys/.../0000:00:1c.0/link/max_speed # RO possible rework > > /sys/.../0000:00:1c.0/link/max_width # RO possible rework > > > > With these backwards compatibility symlinks: > > > > /sys/.../0000:00:1c.0/max_link_speed -> link/max_speed > > /sys/.../0000:00:1c.0/current_link_speed -> link/speed > > > > Rajat's current patch puts the AER stats here at the top level: > > > > /sys/.../0000:00:1c.0/aer_stats/fatal_bit4_DLP > > > > But maybe we could push them down like this: > > > > /sys/.../0000:00:1c.0/errors/aer/stats/unc_04_dlp > > /sys/.../0000:00:1c.0/errors/aer/stats/unc_26_poison_tlb_blocked > > /sys/.../0000:00:1c.0/errors/aer/stats/cor_00_rx_err > > /sys/.../0000:00:1c.0/errors/aer/stats/cor_15_hdr_log_overflow > > How do we create sub-sub-sub directories in sysfs (errors/aer/stats)? You should not. > My understanding is that we can only create 1 subdirectory by using a > "named" attribute group. If we want more hierarchy, the "errors" and > the "aer" will need to be backed up by a kobject. Doable, but just > mentioning. Not doable, you break userspace tools as they will not "see" those directories or attributes. Keep it only 1 deep if at all possible please. thanks, greg k-h
