[RFC] amdgpu MST questions, and future plans

Lyude Paul lyude at redhat.com
Thu Jan 20 06:13:28 UTC 2022

On Wed, 2022-01-19 at 17:56 -0500, Lyude Paul wrote:
> Hi! I'm writing this email because I'm currently finishing up removing
> pretty
> much all of the non-atomic MST code in drm_dp_mst_topology_mgr.c as it's
> really made it difficult to maintain MST over time. As well, once that's
> complete it's likely I'm going to start on the (extremely overdue) task of
> moving as much of amdgpu's MST code for DSC out of amdgpu and into the DRM
> code where it's supposed to live.
> This brings me to two questions. The first major one being: is anyone
> capable
> of testing the MST support in radeon.ko to figure out whether it works or
> not?
> I've already talked with hwentlan and ag5df about this and they haven't been
> able to find anyone to help with testing this. The reason I ask is because
> radeon isn't an atomic driver, and is basically the only user of any of the
> non-atomic parts of the MST helpers. If anyone want to prevent this from
> breaking in the future, I would definitely recommend they step up to try and
> help with testing it - otherwise I'm probably going to be pushing for us
> just
> to drop the code entirely.
> The second question is: is anyone willing to help me figure out how much of
> the code in amdgpu related to DSC is definitely not amdgpu specific and can
> be
> moved out? I'm honestly having a lot of trouble wrapping my head around how
> some of this works, and how much of this code is even needed. As well, with
> the amount of issues I've already found in it (there's numerous spots where
> we're storing MST state outside of atomic state for instance, lots of
> duplicates of DP helper functions that should not be here, etc.) it's quite
> likely I'm going to be rewriting rather large chunks of it. If anyone would

mhhh - on second thought I think I'm starting to wrap my head around this and
it's not actually too bad :), still could use some help with the radeon
testing though!

> like to volunteer please let me know, it'd be super appreciated and likely
> will make reviewing the patches that will come out of this easier.

 Lyude Paul (she/her)
 Software Engineer at Red Hat

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