[Intel-gfx] [PATCH 11/11] drm/i915: Don't modeset with old mode when set_crtc fails

[shuang.he at intel.com]

Tested-By: Intel Graphics QA PRTS (Patch Regression Test System Contact: shuang.he at intel.com)
Task id: 6169
-------------------------------------Summary-------------------------------------
Platform          Delta          drm-intel-nightly          Series Applied
PNV                 -5              276/276              271/276
ILK                                  301/301              301/301
SNB                 -1              316/316              315/316
IVB                 -1              328/328              327/328
BYT                                  285/285              285/285
HSW                                  394/394              394/394
BDW                                  321/321              321/321
-------------------------------------Detailed-------------------------------------
Platform  Test                                drm-intel-nightly          Series Applied
 PNV  igt at gem_userptr_blits@coherency-unsync      CRASH(1)PASS(2)      CRASH(2)
 PNV  igt at gen3_render_linear_blits      FAIL(2)PASS(1)      FAIL(2)
 PNV  igt at gen3_render_mixed_blits      FAIL(2)PASS(1)      FAIL(2)
 PNV  igt at gen3_render_tiledx_blits      FAIL(2)PASS(1)      FAIL(2)
 PNV  igt at gen3_render_tiledy_blits      FAIL(2)PASS(1)      FAIL(2)
 SNB  igt at kms_flip@modeset-vs-vblank-race      DMESG_WARN(1)PASS(3)      DMESG_WARN(1)PASS(1)
(dmesg patch applied)drm:intel_dp_start_link_train[i915]]*ERROR*failed_to_enable_link_training at failed to enable link training
drm:intel_dp_complete_link_train[i915]]*ERROR*failed_to_start_channel_equalization at failed to start channel equalization
drm:intel_dp_start_link_train[i915]]*ERROR*too_many_voltage_retries,give_up at too many voltage .* give up
drm:intel_dp_complete_link_train[i915]]*ERROR*failed_to_train_DP,aborting at failed to train .* aborting
 IVB  igt at gem_pwrite_pread@uncached-copy-performance      DMESG_WARN(1)PASS(1)      DMESG_WARN(2)
(dmesg patch applied)drm:i915_hangcheck_elapsed[i915]]*ERROR*Hangcheck_timer_elapsed...blitter_ring_idle at Hangcheck timer elapsed... blitter ring idle
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