[Intel-gfx] [PATCH v4] drm/i915: Fallback to using unmappable memory for scanout

[shuang.he at intel.com]

Tested-By: PRC QA PRTS (Patch Regression Test System Contact: shuang.he at intel.com)
Task id: 6049
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
PNV                 -6              269/269              263/269
ILK                                  303/303              303/303
SNB                                  304/304              304/304
IVB                                  338/338              338/338
BYT                                  287/287              287/287
HSW                                  362/362              362/362
BDW                                  310/310              310/310
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
 PNV  igt at gem_userptr_blits@coherency-sync      CRASH(3)PASS(3)      CRASH(2)
*PNV  igt at gem_fence_thrash@bo-write-verify-none      PASS(2)      FAIL(1)PASS(1)
 PNV  igt at gem_userptr_blits@minor-unsync-interruptible      DMESG_WARN(1)PASS(3)      DMESG_WARN(1)PASS(1)
WARNING:at_drivers/gpu/drm/i915/i915_gem_evict.c:#i915_gem_evict_vm[i915]()@WARNING:.* at .* i915_gem_evict_vm+0x
 PNV  igt at gem_userptr_blits@minor-unsync-normal      DMESG_WARN(1)PASS(2)      DMESG_WARN(1)PASS(1)
WARNING:at_drivers/gpu/drm/i915/i915_gem_evict.c:#i915_gem_evict_vm[i915]()@WARNING:.* at .* i915_gem_evict_vm+0x
*PNV  igt at gem_fence_thrash@bo-write-verify-threaded-none      PASS(2)      CRASH(1)PASS(1)
*PNV  igt at gem_unfence_active_buffers      PASS(2)      NO_RESULT(1)PASS(1)
Note: You need to pay more attention to line start with '*'