[Intel-gfx] [PATCH 09/13] drm/i915: Extend I915_CONTEXT_PARAM_SSEU to support local ctx->engine[]

[Tvrtko Ursulin]

On 08/03/2019 16:57, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2019-03-08 16:31:51)
>>
>> On 08/03/2019 14:12, Chris Wilson wrote:
>>> Allow the user to specify a local engine index (as opposed to
>>> class:index) that they can use to refer to a preset engine inside the
>>> ctx->engine[] array defined by an earlier I915_CONTEXT_PARAM_ENGINES.
>>> This will be useful for setting SSEU parameters on virtual engines that
>>> are local to the context and do not have a valid global class:instance
>>> lookup.
>>>
>>> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
>>> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
>>> ---
>>>    drivers/gpu/drm/i915/i915_gem_context.c | 24 ++++++++++++++++++++----
>>>    include/uapi/drm/i915_drm.h             |  3 ++-
>>>    2 files changed, 22 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/i915_gem_context.c b/drivers/gpu/drm/i915/i915_gem_context.c
>>> index 86d9bea6f275..a581c01ffff1 100644
>>> --- a/drivers/gpu/drm/i915/i915_gem_context.c
>>> +++ b/drivers/gpu/drm/i915/i915_gem_context.c
>>> @@ -1313,6 +1313,7 @@ static int set_sseu(struct i915_gem_context *ctx,
>>>        struct drm_i915_gem_context_param_sseu user_sseu;
>>>        struct intel_engine_cs *engine;
>>>        struct intel_sseu sseu;
>>> +     unsigned long lookup;
>>
>> Poor 32-bit builds. ;) And in lookup_user_engine as well.
> 
> It's an internal flags variable; not a direct part of the uABI. So it's
> only use is to control lookup_user_engine() so limiting it to 32b
> (natural register width) doesn't seem a like a concern for the
> forseeable future? How many different ABI interfacing methods of looking
> up an engine do you have planned?

I actually wanted to say we could get away with 32-bits for internal 
representation but said the completely opposite thing. :)

Regards,

Tvrtko