[PATCH v4 3/3] drm/amdgpu: Add support for querying the max ibs in a submission. (v3)

[Bas Nieuwenhuizen]

On Fri, Apr 14, 2023 at 11:18 PM Alex Deucher <alexdeucher at gmail.com> wrote:
>
> On Thu, Apr 13, 2023 at 10:25 AM Bas Nieuwenhuizen
> <bas at basnieuwenhuizen.nl> wrote:
> >
> > This info would be used by radv to figure out when we need to
> > split a submission into multiple submissions. radv currently has
> > a limit of 192 which seems to work for most gfx submissions, but
> > is way too high for e.g. compute or sdma.
> >
> > Userspace is available at
> > https://gitlab.freedesktop.org/bnieuwenhuizen/mesa/-/commits/ib-rejection-v3
> >
> > v3: Completely rewrote based on suggestion of making it a separate query.
> >
> > Link: https://gitlab.freedesktop.org/drm/amd/-/issues/2498
> > Signed-off-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
>
> Maybe a 4th patch to bump the driver version?

In the userspace I just make the query and put in some guessed values
if it errors out,  which doesn't need the driver version enumeration.

>
> Alex
>
> > ---
> >  drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c | 9 +++++++++
> >  include/uapi/drm/amdgpu_drm.h           | 2 ++
> >  2 files changed, 11 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> > index 0efb38539d70..1a2e342af1c0 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_kms.c
> > @@ -1140,6 +1140,15 @@ int amdgpu_info_ioctl(struct drm_device *dev, void *data, struct drm_file *filp)
> >                 kfree(caps);
> >                 return r;
> >         }
> > +       case AMDGPU_INFO_MAX_IBS: {
> > +               uint32_t max_ibs[AMDGPU_HW_IP_NUM];
> > +
> > +               for (i = 0; i < AMDGPU_HW_IP_NUM; ++i)
> > +                       max_ibs[i] = amdgpu_ring_max_ibs(i);
> > +
> > +               return copy_to_user(out, max_ibs,
> > +                                   min((size_t)size, sizeof(max_ibs))) ? -EFAULT : 0;
> > +       }
> >         default:
> >                 DRM_DEBUG_KMS("Invalid request %d\n", info->query);
> >                 return -EINVAL;
> > diff --git a/include/uapi/drm/amdgpu_drm.h b/include/uapi/drm/amdgpu_drm.h
> > index b6eb90df5d05..6981e59a9401 100644
> > --- a/include/uapi/drm/amdgpu_drm.h
> > +++ b/include/uapi/drm/amdgpu_drm.h
> > @@ -876,6 +876,8 @@ struct drm_amdgpu_cs_chunk_data {
> >         #define AMDGPU_INFO_VIDEO_CAPS_DECODE           0
> >         /* Subquery id: Encode */
> >         #define AMDGPU_INFO_VIDEO_CAPS_ENCODE           1
> > +/* Query the max number of IBs per gang per submission */
> > +#define AMDGPU_INFO_MAX_IBS                    0x22
> >
> >  #define AMDGPU_INFO_MMR_SE_INDEX_SHIFT 0
> >  #define AMDGPU_INFO_MMR_SE_INDEX_MASK  0xff
> > --
> > 2.40.0
> >