According to the CI test machines, SNB also uses the
GEN7_PCODE_MIN_FREQ_TABLE_GT_RATIO_OUT_OF_RANGE value to report a bad
GEN6_PCODE_MIN_FREQ_TABLE request.

[  157.744641] WARNING: CPU: 5 PID: 9238 at
drivers/gpu/drm/i915/intel_pm.c:7760 sandybridge_pcode_write+0x141/0x200 [i915]
[  157.744642] Missing switch case (16) in gen6_check_mailbox_status
[  157.744642] Modules linked in: snd_hda_intel i915 ax88179_178a usbnet mii x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel snd_hda_codec_hdmi snd_hda_codec_realtek snd_hda_codec_generic snd_hda_codec snd_hwdep snd_hda_core mei_me lpc_ich snd_pcm mei broadcom bcm_phy_lib tg3 ptp pps_core [last unloaded: vgem]
[  157.744658] CPU: 5 PID: 9238 Comm: drv_hangman Tainted: G     U  W 4.8.0-rc3-CI-CI_DRM_1589+ #1
[  157.744658] Hardware name: Dell Inc. XPS 8300  /0Y2MRG, BIOS A06 10/17/2011
[  157.744659]  0000000000000000 ffff88011f093a98 ffffffff81426415 ffff88011f093ae8
[  157.744662]  0000000000000000 ffff88011f093ad8 ffffffff8107d2a6 00001e50810d3c9f
[  157.744663]  ffff880128680000 0000000000000008 0000000000000000 ffff88012868a650
[  157.744665] Call Trace:
[  157.744669]  [<ffffffff81426415>] dump_stack+0x67/0x92
[  157.744672]  [<ffffffff8107d2a6>] __warn+0xc6/0xe0
[  157.744673]  [<ffffffff8107d30a>] warn_slowpath_fmt+0x4a/0x50
[  157.744685]  [<ffffffffa0029831>] sandybridge_pcode_write+0x141/0x200 [i915]
[  157.744697]  [<ffffffffa002a88a>] intel_enable_gt_powersave+0x64a/0x1330 [i915]
[  157.744712]  [<ffffffffa006b4cb>] ? i9xx_emit_request+0x1b/0x80 [i915]
[  157.744725]  [<ffffffffa0055ed3>] __i915_add_request+0x1e3/0x370 [i915]
[  157.744738]  [<ffffffffa00428bd>] i915_gem_do_execbuffer.isra.16+0xced/0x1b80 [i915]
[  157.744740]  [<ffffffff811a232e>] ? __might_fault+0x3e/0x90
[  157.744752]  [<ffffffffa0043b72>] i915_gem_execbuffer2+0xc2/0x2a0 [i915]
[  157.744753]  [<ffffffff815485b7>] drm_ioctl+0x207/0x4c0
[  157.744765]  [<ffffffffa0043ab0>] ? i915_gem_execbuffer+0x360/0x360 [i915]
[  157.744767]  [<ffffffff810ea4ad>] ?  debug_lockdep_rcu_enabled+0x1d/0x20
[  157.744769]  [<ffffffff811fe09e>] do_vfs_ioctl+0x8e/0x680
[  157.744770]  [<ffffffff811a2377>] ? __might_fault+0x87/0x90
[  157.744771]  [<ffffffff811a232e>] ? __might_fault+0x3e/0x90
[  157.744773]  [<ffffffff810d3df2>] ?  trace_hardirqs_on_caller+0x122/0x1b0
[  157.744774]  [<ffffffff811fe6cc>] SyS_ioctl+0x3c/0x70
[  157.744776]  [<ffffffff8180fe69>] entry_SYSCALL_64_fastpath+0x1c/0xac

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=97491
Fixes: 87660502 ("drm/i915/gen6+: Interpret mailbox error flags")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Lyude <cpaul@redhat.com>
Cc: Matt Roper <matthew.d.roper@intel.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: stable@vger.kernel.org
Link: http://patchwork.freedesktop.org/patch/msgid/20160826105926.3413-1-chris@chris-wilson.co.ukAcked-by: Mika Kuoppala <mika.kuoppala@intel.com>