Re: [PATCH 2/3] drm/i915: Store engine mask in intel_gt

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 16/10/2019 14:03, Chris Wilson wrote:
> Quoting Tvrtko Ursulin (2019-10-16 13:28:42)
>> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>>
>> Medium term goal is to eliminate the i915->engine[] array and to get there
>> we have recently introduced equivalent array in intel_gt. Now we need to
>> migrate the code further towards this state.
>>
>> To allow for_each_engine_masked call sites to pass in gt instead of i915
>> we need to have a copy of INTEL_INFO()->engine_mask in intel_gt.
>>
>> For this to work we also need to use engine->id as index when populating
>> the gt->engine[] array.
>>
>> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>> ---
>>   drivers/gpu/drm/i915/gt/intel_engine_user.c | 4 ++--
>>   drivers/gpu/drm/i915/gt/intel_gt.c          | 5 +++++
>>   drivers/gpu/drm/i915/gt/intel_gt.h          | 1 +
>>   drivers/gpu/drm/i915/gt/intel_gt_types.h    | 4 ++++
>>   drivers/gpu/drm/i915/i915_drv.c             | 2 ++
>>   5 files changed, 14 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_user.c b/drivers/gpu/drm/i915/gt/intel_engine_user.c
>> index 77cd5de83930..099abae860ec 100644
>> --- a/drivers/gpu/drm/i915/gt/intel_engine_user.c
>> +++ b/drivers/gpu/drm/i915/gt/intel_engine_user.c
>> @@ -183,8 +183,8 @@ static void add_legacy_ring(struct legacy_ring *ring,
>>          if (unlikely(idx == -1))
>>                  return;
>>   
>> -       GEM_BUG_ON(idx >= ARRAY_SIZE(ring->gt->engine));
>> -       ring->gt->engine[idx] = engine;
> 
> This is used for the legacy uapi mapping. So we need to adjust the loop
> in i915_gem_context.c::default_engines() to use engine->legacy_idx
> instead of id. And all other users of engine->legacy_idx are now
> backwards.

Hmmm that's evil.. I mean so well hidden dependency and contrary to 
years of decoupling efforts. But I gather some mess is expected in these 
circumstances. I'll update.

Regards,

Tvrtko

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