On Fri, 12 Aug 2022 11:06:58 -0700, Guenter Roeck wrote: > Hi Guenter/linux-hwmon, > On 8/12/22 10:37, Badal Nilawar wrote: > > From: Dale B Stimson <dale.b.stimson@xxxxxxxxx> > > > > Use i915 HWMON to display/modify dGfx power PL1 limit and TDP setting. > > /snip/ > > Acked-by: Guenter Roeck <linux@xxxxxxxxxxxx> > > > --- > > .../ABI/testing/sysfs-driver-intel-i915-hwmon | 20 ++ > > drivers/gpu/drm/i915/i915_hwmon.c | 176 +++++++++++++++++- > > drivers/gpu/drm/i915/i915_reg.h | 16 ++ > > drivers/gpu/drm/i915/intel_mchbar_regs.h | 7 + > > 4 files changed, 217 insertions(+), 2 deletions(-) > > > > diff --git a/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon b/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon > > index 24c4b7477d51..9a2d10edfce8 100644 > > --- a/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon > > +++ b/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon > > @@ -5,3 +5,23 @@ Contact: dri-devel@xxxxxxxxxxxxxxxxxxxxx > > Description: RO. Current Voltage in millivolt. > > Only supported for particular Intel i915 graphics > > platforms. > > + > > +What: /sys/devices/.../hwmon/hwmon<i>/power1_max > > +Date: June 2022 > > +KernelVersion: 5.19 > > +Contact: dri-devel@xxxxxxxxxxxxxxxxxxxxx > > +Description: RW. Card reactive sustained (PL1/Tau) power limit in microwatts. > > + > > + The power controller will throttle the operating frequency > > + if the power averaged over a window (typically seconds) > > + exceeds this limit. We exposed this as 'power1_max' previously. However this is a "power limit". https://github.com/torvalds/linux/blob/master/Documentation/hwmon/sysfs-interface.rst says power1_max is "Maximum power". On the other hand, power1_cap is "If power use rises above this limit, the system should take action to reduce power use". So it would seem we should have chosen power1_cap for this power limit instead of power1_max? So do you think we should change this to power1_cap instead? Though even power1_max has an associated alarm so it also seems to be a sort of limit. Is there any guidance as to how these different power limits should be used? Generally speaking is: power1_max <= power1_cap <= power1_crit, or is it arbitrary or something else? Also, only power1_cap seems to have power1_cap_min and power1_cap_max (in case we wanted to use min/max values for the limits), not the others. Separately, we have already used up power1_crit (which is the other limit in official hwmon power limits) so we can't use that. Thanks. -- Ashutosh
