[Intel-gfx] [PATCH] drm/i915/ehl: Add missing VECS engine

[Tvrtko Ursulin]

On 25/06/2019 22:48, Daniele Ceraolo Spurio wrote:
> On 6/25/19 8:26 AM, Matt Roper wrote:
>> On Fri, Jun 14, 2019 at 03:17:39PM -0700, Matt Roper wrote:
>>> On Fri, Jun 14, 2019 at 02:37:49PM -0700, José Roberto de Souza wrote:
>>>> EHL can have up to one VECS(video enhancement) engine, so add it to
>>>> the device_info.
>>>
>>> Bspec 29150 has a footnote on VEbox that indicates "Pass-through only,
>>> no VEbox processing logic."  That note seems a bit vague, but I think I
>>> saw some more detailed info in the past somewhere that indicated the
>>> VECS command streamer is still technically present but doesn't actually
>>> do any video enhancement on EHL; it just passes content through to SFC.
>>>
>>> I'm not terribly plugged into the media side of the world, so I'm not
>>> sure if we want to expose VECS to userspace if it's basically a noop and
>>> doesn't do what it normally does on other platforms.  Bspec page 5229
>>> implies that SFC can be fed directly by the decode engine without going
>>> through VEBOX, so I'm not sure if media userspace would ever have a use
>>> for the passthrough-only VECS streamer.
>>>
>>> We should probably ask someone on the media team what their thoughts are
>>> on this.
>>
>> Since the media team confirmed that there is indeed a use case for a
>> passthrough-only VECS,
>>
>> Reviewed-by: Matt Roper <matthew.d.roper at intel.com>
>>
> 
> A bit late for a question, but how does userspace know that this is just 
> a pass-through VECS? Are we expecting them to switch based on platform 
> instead of just using the kernel API? IMO it'd be better to hide the 
> engine in the query ioctl by default and only show it if userspace 
> passes an appropriate flag, otherwise legacy apps could try to submit 
> VECS-specific commands to the engine.

I have a patch which would enable this, guess it's time to send it..

If we go this route (hide the engine by default), this patch would need 
to add a new capability flag. But what to call it? 
I915_VIDEO_ENHANCE_CLASS_PASSTHROUGH?

Regards,

Tvrtko