RE: [PATCH] drm/amd/pm: Fix incorrect avg vcn utilization in gpu_metrics

AMD General

> -----Original Message-----
> From: Alex Deucher <[email protected]>
> Sent: Friday, August 14, 2026 8:51 AM
> To: Boqun Feng <[email protected]>
> Cc: [email protected]; Mark Janes <[email protected]>; Feng,
> Kenneth <[email protected]>; Deucher, Alexander
> <[email protected]>; Koenig, Christian
> <[email protected]>; David Airlie <[email protected]>; Simona
> Vetter <[email protected]>; Lazar, Lijo <[email protected]>; Kamal, Asad
> <[email protected]>; Wang, Yang(Kevin) <[email protected]>;
> Hosur, Priya <[email protected]>; M, Mythila <[email protected]>;
> Limonciello, Mario <[email protected]>; dri-
> [email protected]; [email protected]; Umio Yasuno
> <[email protected]>
> Subject: Re: [PATCH] drm/amd/pm: Fix incorrect avg vcn utilization in
> gpu_metrics
>
> On Thu, Aug 13, 2026 at 6:25 PM Boqun Feng <[email protected]> wrote:
> >
> > On Thu, Aug 13, 2026 at 06:01:47PM -0400, Alex Deucher wrote:
> > > On Thu, Aug 13, 2026 at 5:36 PM Boqun Feng <[email protected]> wrote:
> > > >
> > > > On Wed, Aug 05, 2026 at 07:02:21AM -0700, Boqun Feng wrote:
> > > > > In a Strix Halo system, a >100 average_vcn_activity in
> > > > > gpu_metrics can be observed by running the following command:
> > > > >
> > > > >     ffmpeg -hwaccel vappi -vappi_device /dev/dri/renderD128 -i \
> > > > >     ~/sample-10s.mp4 -vf hwupload,scale_vappi=format=nv12 -c:v \
> > > > >     h264_vappi /tmp/output.mp4
> > > > >
> > > > > This is incorrect because the value is supposed to be in [0-100] range.
> > > > >
> > > > > The cause of the issue is that the metrics.VcnActivity reported
> > > > > by
> > > > > smu_cmn_get_metrics_table() is a permyriad value instead of a
> > > > > percentage value (e.g. smu_v14_0_0_get_smu_metrics_data() has a
> > > > > division by 100 to report the vcn_busy_percent). Therefore fix
> > > > > this by applying the same division in smu_v14_0_0_get_gpu_metrics().
> > >
> > > I think this is correct as is.  smu_v14_0_0_get_smu_metrics_data()
> > > is used to fetch data for standardized formats like hwmon while
> > > smu_v14_0_0_get_gpu_metrics() is for dumping the raw metrics data.
> > >
> >
> > Well, then kgd_pp_interface.h needs some help?
> >
> > struct gpu_metrics_v3_0 {
> >         ...
> >         /* Utilization */
> >         /* time filtered GFX busy % [0-100] */
> >         uint16_t                        average_gfx_activity;
> >         /* time filtered VCN busy % [0-100] */
> >         uint16_t                        average_vcn_activity;
> >         ...
> > }
> >
> > Clearly it's not true.
>
> That was likely copy and pasted from the firmware interface
> (smu14_driver_if_v14_0_0.h):
> uint16_t VcnActivity;                //Time filtered VCN busy % [0-100]
>
> Other generations seem to do the same thing (raw data in metrics table
> and % in the hwmon type interfaces). E.g., smu_v13_0_4_ppt.c:
> smu_v13_0_4_get_gpu_metrics()
> gpu_metrics->average_mm_activity = metrics.UvdActivity; vs
> smu_v13_0_4_get_smu_metrics_data():
> *value = metrics->UvdActivity / 100;

For SMU 14.0.0, the VCN activity value returned from PMFW ranges from 0 to 10000, and the driver shall divide this value by 100 before reporting it.
This scaling does **not** apply to GFX activity.

Best Regards,
Kevin
>
> Alex
>
> >
> > [Cc amdgpu_top]
> >
> > Regards,
> > Boqun
> >
> > > Alex
> > >
> > > > >
> > > > > Reported-by: Mark Janes <[email protected]>
> > > > > Signed-off-by: Boqun Feng <[email protected]>
> > > >
> > > > Ping?
> > > >
> > > > Regards,
> > > > Boqun
> > > >
> > > > > ---
> > > > >  drivers/gpu/drm/amd/pm/swsmu/smu14/smu_v14_0_0_ppt.c | 3 ++-
> > > > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git
> > > > > a/drivers/gpu/drm/amd/pm/swsmu/smu14/smu_v14_0_0_ppt.c
> > > > > b/drivers/gpu/drm/amd/pm/swsmu/smu14/smu_v14_0_0_ppt.c
> > > > > index 568665265a13..1058338344b0 100644
> > > > > --- a/drivers/gpu/drm/amd/pm/swsmu/smu14/smu_v14_0_0_ppt.c
> > > > > +++ b/drivers/gpu/drm/amd/pm/swsmu/smu14/smu_v14_0_0_ppt.c
> > > > > @@ -566,7 +566,8 @@ static ssize_t
> smu_v14_0_0_get_gpu_metrics(struct smu_context *smu,
> > > > >       gpu_metrics->temperature_skin = metrics.SkinTemp;
> > > > >
> > > > >       gpu_metrics->average_gfx_activity = metrics.GfxActivity;
> > > > > -     gpu_metrics->average_vcn_activity = metrics.VcnActivity;
> > > > > +     /* metrics.VcnActivity is permyriad, convert it to percentage. */
> > > > > +     gpu_metrics->average_vcn_activity = metrics.VcnActivity /
> > > > > + 100;
> > > > >       memcpy(&gpu_metrics->average_ipu_activity[0],
> > > > >               &metrics.IpuBusy[0],
> > > > >               sizeof(uint16_t) * 8);
> > > > > --
> > > > > 2.50.1 (Apple Git-155)
> > > > >