[Intel-gfx] [PATCH] drm/i915: Prevent use of global_seqno=0

[Mika Kuoppala]

Chris Wilson <chris at chris-wilson.co.uk> writes:

> We are not allowed to assign rq->global_seqno=0 as it has a special
> meaning of "inactive" (not executing on HW).
>
> Fixes: 6faf5916e6be ("drm/i915: Remove HW semaphores for gen7 inter-engine synchronisation")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Mika Kuoppala <mika.kuoppala at linux.intel.com>

Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

> ---
>  drivers/gpu/drm/i915/i915_request.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_request.c b/drivers/gpu/drm/i915/i915_request.c
> index 5403d4e2cee0..5e178f5ac18b 100644
> --- a/drivers/gpu/drm/i915/i915_request.c
> +++ b/drivers/gpu/drm/i915/i915_request.c
> @@ -343,6 +343,13 @@ static void move_to_timeline(struct i915_request *request,
>  	spin_unlock(&request->timeline->lock);
>  }
>  
> +static u32 next_global_seqno(struct i915_timeline *tl)
> +{
> +	if (!++tl->seqno)
> +		++tl->seqno;
> +	return tl->seqno;
> +}
> +
>  void __i915_request_submit(struct i915_request *request)
>  {
>  	struct intel_engine_cs *engine = request->engine;
> @@ -359,7 +366,7 @@ void __i915_request_submit(struct i915_request *request)
>  
>  	GEM_BUG_ON(request->global_seqno);
>  
> -	seqno = timeline_get_seqno(&engine->timeline);
> +	seqno = next_global_seqno(&engine->timeline);
>  	GEM_BUG_ON(!seqno);
>  	GEM_BUG_ON(intel_engine_signaled(engine, seqno));
>  
> -- 
> 2.20.1