According to BSpec the Data Island Packet should be disabled after
disabling the transcoder, but before the transcoder clock select is set
to none. On an ICL RVP, daisy-chained MST config not following this
leads to a hang with the following MCE when disabling the output:
[ 870.948739] mce: [Hardware Error]: CPU 0: Machine Check Exception: 5 Bank 6: ba00000011000402
[ 871.019212] mce: [Hardware Error]: RIP !INEXACT! 10:<ffffffff81aca652> {poll_idle+0x92/0xb0}
[ 871.019212] mce: [Hardware Error]: TSC 135a261fe61
[ 871.019212] mce: [Hardware Error]: PROCESSOR 0:706e5 TIME 1591739604 SOCKET 0 APIC 0 microcode 20
[ 871.019212] mce: [Hardware Error]: Run the above through 'mcelog --ascii'
[ 871.019212] mce: [Hardware Error]: Machine check: Processor context corrupt
[ 871.019212] Kernel panic - not syncing: Fatal machine check
[ 871.019212] Kernel Offset: disabled
Bspec: 4287
Fixes: fa37a21327 ("drm/i915: Stop sending DP SDPs on ddi disable")
Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Uma Shankar <uma.shankar@intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Uma Shankar <uma.shankar@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20200609220616.6015-1-imre.deak@intel.com
(cherry picked from commit c980216dd2)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
898e4e57ad