Re: [Intel-gfx] [PATCH 14/46] drm/i915: Expose logical engine instance to user

Daniel Vetter
2021-08-09T14:30:12Z

On Tue, Aug 03, 2021 at 03:29:11PM -0700, Matthew Brost wrote:
> Expose logical engine instance to user via query engine info IOCTL. This
> is required for split-frame workloads as these needs to be placed on
> engines in a logically contiguous order. The logical mapping can change
> based on fusing. Rather than having user have knowledge of the fusing we
> simply just expose the logical mapping with the existing query engine
> info IOCTL.
>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>

Uapi must have a link to the userspace MR/patch set using this, and to the
igt patch set validating it.

Ideally in each patch, since it's way too hard to unfortunately find the
cover letter late on.

Jason even went as far as making this a hard requirement because he wasted
a bit too much time trying to find the userspace for new uapi:

https://lore.kernel.org/dri-devel/20210804185704.624883-1-jason@jlekstrand.net/

Cheers, Daniel

>---
> drivers/gpu/drm/i915/i915_query.c | 2 ++
> include/uapi/drm/i915_drm.h | 8 +++++++-
> 2 files changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_query.c b/drivers/gpu/drm/i915/i915_query.c
> index e49da36c62fb..8a72923fbdba 100644
> --- a/drivers/gpu/drm/i915/i915_query.c
> +++ b/drivers/gpu/drm/i915/i915_query.c
> @@ -124,7 +124,9 @@ query_engine_info(struct drm_i915_private *i915,
> for_each_uabi_engine(engine, i915) {
> info.engine.engine_class = engine->uabi_class;
> info.engine.engine_instance = engine->uabi_instance;
> + info.flags = I915_ENGINE_INFO_HAS_LOGICAL_INSTANCE;
> info.capabilities = engine->uabi_capabilities;
> + info.logical_instance = ilog2(engine->logical_mask);
>
> if (copy_to_user(info_ptr, &info, sizeof(info)))
> return -EFAULT;
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 7f13d241417f..ef72e07fe08c 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -2706,14 +2706,20 @@ struct drm_i915_engine_info {
>
> /** @flags: Engine flags. */
> __u64 flags;
> +#define I915_ENGINE_INFO_HAS_LOGICAL_INSTANCE (1 << 0)
>
> /** @capabilities: Capabilities of this engine. */
> __u64 capabilities;
> #define I915_VIDEO_CLASS_CAPABILITY_HEVC (1 << 0)
> #define I915_VIDEO_AND_ENHANCE_CLASS_CAPABILITY_SFC (1 << 1)
>
> + /** @logical_instance: Logical instance of engine */
> + __u16 logical_instance;
> +
> /** @rsvd1: Reserved fields. */
> - __u64 rsvd1[4];
> + __u16 rsvd1[3];
> + /** @rsvd2: Reserved fields. */
> + __u64 rsvd2[3];
> };
>
> /**
> --
> 2.28.0
>

--
Daniel Vetter
Software Engineer, Intel Corporation