[PATCH 0/4][SRU][Noble] Unexpected system reboot at loading GUI session on some AMD platforms

[You-Sheng Yang]

BugLink: https://bugs.launchpad.net/bugs/2112462

[ Impact ]

AMD Strix Halo devices experience unexpected reboots while starting GUI
session every boot.

This is caused by:
* 689275140cb8e drm/amdgpu/hdp7.0: do a posting read when flushing HDP
* abe1cbaec6cfe drm/amdgpu/hdp6.0: do a posting read when flushing HDP
* f756dbac1ce1d drm/amdgpu/hdp5.2: do a posting read when flushing HDP
* cf424020e040b drm/amdgpu/hdp5.0: do a posting read when flushing HDP
* c9b8dcabb52af drm/amdgpu/hdp4.0: do a posting read when flushing HDP

And fixed by:
* 5a11a27677311 drm/amdgpu/hdp7: use memcfg register to post the write for HDP flush
* ca28e80abe421 drm/amdgpu/hdp6: use memcfg register to post the write for HDP flush
* dbc988c689333 drm/amdgpu/hdp5.2: use memcfg register to post the write for HDP flush
* 0e33e0f339b91 drm/amdgpu/hdp5: use memcfg register to post the write for HDP flush
* f690e3974755a drm/amdgpu/hdp4: use memcfg register to post the write for HDP flush

[ Test Plan ]

1. Install -proposed kernel
2. Reboot to the installed kernel and check if the device may finish boot
   process to GUI session.

[ Where problems could occur ]

No. This fix a problem when reading back the whole mapped
KFD_MMIO_REMAP_HDP_MEM_FLUSH_CNTL register by reading another register that
also triggers the flush.

[ Other Info ]

The causing commits were first committed to v6.13-rc1 , and have also been
backported to v6.12.5, v6.6.69, v6.1.120. The fixes are available in
v6.15-rc6, also backported to v6.14.7, v6.12.29, v6.6.91, v6.1.139,
therefore this affects following Ubuntu kernels:
* linux/plucky: all (currently 6.14.0-22.22)
* linux-oem-6.14/noble: all (currently 6.14.0-1005.5)
* linux/oracular: 6.11.0-20.20 to latest (currently 6.11.0-28.28)
* linux-oem-6.11/noble: 6.11.0-1017.17 to latest (currently 6.11.0-1024.24)
* linux/noble: 6.8.0-58.60 to latest (currently 6.8.0-62.65)
* linux-oem-6.8/noble: 6.8.0-1026.26 to latest (currently 6.8.0-1029.29)

Nominate for linux/noble, linux-oem-6.8/noble, linux/oracular,
linux-oem-6.11/noble, linux/plucky, and linux-oem-6.14/noble.

Alex Deucher (4):
  drm/amdgpu/hdp4: use memcfg register to post the write for HDP flush
  drm/amdgpu/hdp5: use memcfg register to post the write for HDP flush
  drm/amdgpu/hdp5.2: use memcfg register to post the write for HDP flush
  drm/amdgpu/hdp6: use memcfg register to post the write for HDP flush

 drivers/gpu/drm/amd/amdgpu/hdp_v4_0.c |  7 ++++++-
 drivers/gpu/drm/amd/amdgpu/hdp_v5_0.c |  7 ++++++-
 drivers/gpu/drm/amd/amdgpu/hdp_v5_2.c | 12 +++++++++++-
 drivers/gpu/drm/amd/amdgpu/hdp_v6_0.c |  7 ++++++-
 4 files changed, 29 insertions(+), 4 deletions(-)

-- 
2.48.1