Re: [Nouveau] [PATCH] drm/nouveau: Add fine-grain temperature reporting

From: Karol Herbst
Date: Wed Sep 09 2020 - 04:22:37 EST


On Wed, Sep 9, 2020 at 6:06 AM Ben Skeggs <skeggsb@xxxxxxxxx> wrote:
>
> On Thu, 13 Aug 2020 at 06:50, Jeremy Cline <jcline@xxxxxxxxxx> wrote:
> >
> > Commit d32656373857 ("drm/nouveau/therm/gp100: initial implementation of
> > new gp1xx temperature sensor") added support for reading finer-grain
> > temperatures, but continued to report temperatures in 1 degree Celsius
> > increments via nvkm_therm_temp_get().
> >
> > Rather than altering nvkm_therm_temp_get() to report finer-grain
> > temperatures, which would be inconvenient for other users of the
> > function, a second interface has been added to line up with hwmon's
> > native unit of temperature.
> Hey Jeremy,
>
> Sorry this slipped past me until now. I'm OK with adding support for
> millidegree temperature reporting, but don't think we need to keep
> both interfaces around and would rather see the existing code
> converted to return millidegrees (even on GPUs that don't support it)
> instead of degrees.
>
> Thanks!
> Ben.
>

just a note as I was trying something like that in the past: we have a
lot of code which fetches the temperature and there are a lot of
places where we would then do a divide by 1000, so having a wrapper
function at least makes sense. If we want to keep the func pointers?
well.. I guess the increased CPU overhead wouldn't be as bad if all
sub classes do this static * 1000 as well either. I just think we
should have both interfaces in subdev/therm.h so we can just keep most
of the current code as is.

> >
> > Signed-off-by: Jeremy Cline <jcline@xxxxxxxxxx>
> > ---
> > .../drm/nouveau/include/nvkm/subdev/therm.h | 18 +++++++++++++
> > drivers/gpu/drm/nouveau/nouveau_hwmon.c | 4 +--
> > .../gpu/drm/nouveau/nvkm/subdev/therm/base.c | 16 ++++++++++++
> > .../gpu/drm/nouveau/nvkm/subdev/therm/gp100.c | 25 +++++++++++++++++--
> > .../gpu/drm/nouveau/nvkm/subdev/therm/priv.h | 1 +
> > 5 files changed, 60 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/nouveau/include/nvkm/subdev/therm.h b/drivers/gpu/drm/nouveau/include/nvkm/subdev/therm.h
> > index 62c34f98c930..7b9928dd001c 100644
> > --- a/drivers/gpu/drm/nouveau/include/nvkm/subdev/therm.h
> > +++ b/drivers/gpu/drm/nouveau/include/nvkm/subdev/therm.h
> > @@ -100,6 +100,24 @@ struct nvkm_therm {
> > };
> >
> > int nvkm_therm_temp_get(struct nvkm_therm *);
> > +
> > +/**
> > + * nvkm_therm_temp_millidegree_get() - get the temperature in millidegrees
> > + * @therm: The thermal device to read from.
> > + *
> > + * This interface reports temperatures in units of millidegree Celsius to
> > + * align with the hwmon API. Some cards may only be capable of reporting in
> > + * units of Celsius, and those that report finer grain temperatures may not be
> > + * capable of millidegree Celsius accuracy,
> > + *
> > + * For cases where millidegree temperature is too fine-grain, the
> > + * nvkm_therm_temp_get() interface reports temperatures in one degree Celsius
> > + * increments.
> > + *
> > + * Return: The temperature in millidegrees Celsius, or -ENODEV if temperature
> > + * reporting is not supported.
> > + */
> > +int nvkm_therm_temp_millidegree_get(struct nvkm_therm *therm);
> > int nvkm_therm_fan_sense(struct nvkm_therm *);
> > int nvkm_therm_cstate(struct nvkm_therm *, int, int);
> > void nvkm_therm_clkgate_init(struct nvkm_therm *,
> > diff --git a/drivers/gpu/drm/nouveau/nouveau_hwmon.c b/drivers/gpu/drm/nouveau/nouveau_hwmon.c
> > index 1c3104d20571..e96355f93ce5 100644
> > --- a/drivers/gpu/drm/nouveau/nouveau_hwmon.c
> > +++ b/drivers/gpu/drm/nouveau/nouveau_hwmon.c
> > @@ -428,8 +428,8 @@ nouveau_temp_read(struct device *dev, u32 attr, int channel, long *val)
> > case hwmon_temp_input:
> > if (drm_dev->switch_power_state != DRM_SWITCH_POWER_ON)
> > return -EINVAL;
> > - ret = nvkm_therm_temp_get(therm);
> > - *val = ret < 0 ? ret : (ret * 1000);
> > + ret = nvkm_therm_temp_millidegree_get(therm);
> > + *val = ret;
> > break;
> > case hwmon_temp_max:
> > *val = therm->attr_get(therm, NVKM_THERM_ATTR_THRS_DOWN_CLK)
> > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/therm/base.c b/drivers/gpu/drm/nouveau/nvkm/subdev/therm/base.c
> > index 4a4d1e224126..e655b32c78b8 100644
> > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/therm/base.c
> > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/therm/base.c
> > @@ -34,6 +34,22 @@ nvkm_therm_temp_get(struct nvkm_therm *therm)
> > return -ENODEV;
> > }
> >
> > +int
> > +nvkm_therm_temp_millidegree_get(struct nvkm_therm *therm)
> > +{
> > + int ret = -ENODEV;
> > +
> > + if (therm->func->temp_millidegree_get)
> > + return therm->func->temp_millidegree_get(therm);
> > +
> > + if (therm->func->temp_get) {
> > + ret = therm->func->temp_get(therm);
> > + if (ret > 0)
> > + ret *= 1000;
> > + }
> > + return ret;
> > +}
> > +
> > static int
> > nvkm_therm_update_trip(struct nvkm_therm *therm)
> > {
> > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/therm/gp100.c b/drivers/gpu/drm/nouveau/nvkm/subdev/therm/gp100.c
> > index 9f0dea3f61dc..4c3c2895a3cb 100644
> > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/therm/gp100.c
> > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/therm/gp100.c
> > @@ -24,7 +24,7 @@
> > #include "priv.h"
> >
> > static int
> > -gp100_temp_get(struct nvkm_therm *therm)
> > +gp100_temp_get_raw(struct nvkm_therm *therm)
> > {
> > struct nvkm_device *device = therm->subdev.device;
> > struct nvkm_subdev *subdev = &therm->subdev;
> > @@ -37,14 +37,35 @@ gp100_temp_get(struct nvkm_therm *therm)
> >
> > /* device valid */
> > if (tsensor & 0x20000000)
> > - return (inttemp >> 8);
> > + return inttemp;
> > else
> > return -ENODEV;
> > }
> >
> > +static int
> > +gp100_temp_millidegree_get(struct nvkm_therm *therm)
> > +{
> > + int raw_temp = gp100_temp_get_raw(therm);
> > +
> > + if (raw_temp < 0)
> > + return raw_temp;
> > + return raw_temp * 1000 >> 8;
> > +}
> > +
> > +static int
> > +gp100_temp_get(struct nvkm_therm *therm)
> > +{
> > + int raw_temp = gp100_temp_get_raw(therm);
> > +
> > + if (raw_temp < 0)
> > + return raw_temp;
> > + return raw_temp >> 8;
> > +}
> > +
> > static const struct nvkm_therm_func
> > gp100_therm = {
> > .temp_get = gp100_temp_get,
> > + .temp_millidegree_get = gp100_temp_millidegree_get,
> > .program_alarms = nvkm_therm_program_alarms_polling,
> > };
> >
> > diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/therm/priv.h b/drivers/gpu/drm/nouveau/nvkm/subdev/therm/priv.h
> > index 21659daf1864..a53068b4f0b9 100644
> > --- a/drivers/gpu/drm/nouveau/nvkm/subdev/therm/priv.h
> > +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/therm/priv.h
> > @@ -92,6 +92,7 @@ struct nvkm_therm_func {
> > int (*pwm_clock)(struct nvkm_therm *, int line);
> >
> > int (*temp_get)(struct nvkm_therm *);
> > + int (*temp_millidegree_get)(struct nvkm_therm *therm);
> >
> > int (*fan_sense)(struct nvkm_therm *);
> >
> > --
> > 2.26.2
> >
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