[SRU][OEM-5.14/J][PATCH 0/4] Fix DP tunneling issues on AMD Rembrandt

[Mario Limonciello]

On 8/1/22 03:43, Stefan Bader wrote:
> On 29.07.22 20:56, Mario Limonciello wrote:
>> BugLink: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1983143
>>
>> When a Thunderbolt monitor or Thunderbolt dock are connected to a USB4
>> port on AMD Yellow Carp (Rembrandt) a software connection manager works
>> with the hardware to initialize tunnels.
>>
>> One of those tunnels is for DP (display port). It was observed that
>> on both the OEM-5.14 as well as Jammy-5.15 kernel that DP tunneling
>> specifically when connecting to a Thunderbolt monitor fails.
>> This circumstance does not happen on OEM-5.17 or mainline kernels.
>>
>> This is due to a backport error on the USB4 patch series that went
>> into OEM-5.14 and moved forward to Jammy-5.15.  Patch 1/4 in this
>> series corrects that error as minimally as possible as a SAUCE patch.
>>
>> It was also observed that DP tunneling is not working for Thunderbolt
>> monitor connected at boot, but this is a different root cause.
>> The "Pre-OS" connection manager creates DP tunnels that are expected
>> to be re-used by the OS connection manager. The remaining patches in
>> this series enable this flow.
>>
>> For this whole flow to work an updated AMDGPU DMCUB firmware is also
>> needed.  This is already in process as part of:
>> https://bugs.launchpad.net/ubuntu/+source/linux-firmware/+bug/1981922
>>
>> Mario Limonciello (1):
>>    UBUNTU: SAUCE: drm/amd: Fix DP Tunneling with Thunderbolt monitors
> 
> Hi Mario,
> 
> while your patch contains good reasoning for why it is a non-upstream 
> patch, the other SAUCE patch is not that clear. From the s-o-b reference 
> it sounds like it might go upstream which makes one wonder why not 
> taking it from there.

Hi Stefan,

It's due to timing.  It is on it's way upstream, but it just hasn't 
landed yet.  The maintainer has been OOO for the month of July and 
already sent out the PR for 5.20 content much earlier. So consequently 
this is unlikely to be accepted it until 5.21.  This is needed to 
support DP tunneling use cases (docking or connected to TBT monitor) 
across a reboot or cold boot cycle on any RMB platforms.

> 
>>
>> Meenakshikumar Somasundaram (1):
>>    drm/amd/display: Fix for dmub outbox notification enable
>>
>> Sanjay R Mehta (1):
>>    UBUNTU: SAUCE: thunderbolt: Add DP out resource when DP tunnel is
>>      discovered.
>>
>> Stylon Wang (1):
>>    drm/amd/display: Fix new dmub notification enabling in DM
> 
> That one ^ I would rather declare a backport and annotate with short 
> hints about what was worked around. Like "use <name> instead of <other 
> name>". Mentioning which changes are missing is nice in addition but for 
> glancing over submissions it is much simpler to get told what to watch 
> out for.

Sure no problem to me.

> 
> To be clear I am not asking to re-submit. If we can clarify things we 
> can make the adjustments when we apply things.

OK.

> 
> -Stefan
> 
>>
>>   .../gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 24 +++++--
>>   drivers/gpu/drm/amd/display/dc/core/dc.c      | 66 +++++++++++++++++--
>>   drivers/gpu/drm/amd/display/dc/dc.h           |  3 +
>>   .../gpu/drm/amd/display/dc/dce/dmub_outbox.c  | 25 +++----
>>   .../gpu/drm/amd/display/dc/dce/dmub_outbox.h  |  4 +-
>>   .../amd/display/dc/dcn10/dcn10_hw_sequencer.c |  4 --
>>   .../drm/amd/display/dc/dcn20/dcn20_hwseq.c    |  4 ++
>>   .../drm/amd/display/dc/dcn31/dcn31_hwseq.c    |  2 +-
>>   drivers/thunderbolt/tb.c                      | 15 +++++
>>   drivers/thunderbolt/tb.h                      |  1 +
>>   drivers/thunderbolt/tunnel.c                  |  2 +
>>   11 files changed, 121 insertions(+), 29 deletions(-)
>>
>