Comment 10 for bug 1797882

I am using intel i915 gen 3 with 16 fence registers.
When displaying the variable total_fences
at function drm_intel_gem_check_aperture_space at libdrm-2.4.95/intel/intel_bufmgr_gem.c,
it is seen that the deadlock-abort is occurring at total_fences == 16,
where the previous display shows total_fences == 14,
so there is an increment of 2 fences in stead of the usual increment of 1.
Apparently the deadlock occurs at the "freeing fences phase", that is started if total_fences is too high.
I decided to lower the available_fences from 14 to 13 (see proposed patch).
This solved the problem.
After this patch I still saw sometimes total_fences == 16,
where the previous display shows total_fences == 13, so there is an increment of 3 fences. This did not cause a deadlock at the "freeing fences phase".