Re: [Intel-gfx] [PATCH 09/27] drm/i915: Expose logical engine instance to user

From: John Harrison <john.c.harrison@intel.com>
To: Matthew Brost <matthew.brost@intel.com>,
	<intel-gfx@lists.freedesktop.org>,
	<dri-devel@lists.freedesktop.org>
Cc: <daniel.vetter@ffwll.ch>, <tony.ye@intel.com>, <zhengguo.xu@intel.com>
Subject: Re: [Intel-gfx] [PATCH 09/27] drm/i915: Expose logical engine instance to user
Date: Mon, 13 Sep 2021 16:06:33 -0700	[thread overview]
Message-ID: <7f3495e7-d66a-3254-3473-b25e4c757b5c@intel.com> (raw)
In-Reply-To: <20210820224446.30620-10-matthew.brost@intel.com>

On 8/20/2021 15:44, 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.
>
> IGT: https://patchwork.freedesktop.org/patch/445637/?series=92854&rev=1
> media UMD: link coming soon
>
> v2:
>   (Daniel Vetter)
>    - Add IGT link, placeholder for media UMD
>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
>   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 bde5860b3686..b1248a67b4f8 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -2726,14 +2726,20 @@ 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];
>   };
>   
>   /**
Any idea why the padding? Would be useful if the comment said 'this 
structure must be at least/exactly X bytes in size / a multiple of X 
bytes in size because ...' or whatever.

However, not really anything to do with this patch as such, so either way:
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>