Re: [PATCH 0/8] [RFC] Link training test

Daniel Vetter
2015-09-22T15:10:07Z

Thierry Redding is working on some improved dp helper libraries for link
training. Would make lots of sense to have all that aligned. Adding him
and dri-devel.
-Daniel

On Tue, Sep 8, 2015 at 2:27 PM, Ander Conselvan de Oliveira <ander.conselvan.de.oliveira@intel.com> wrote:
> Hi,
>
> There's been some discussion on improving our link training code, with
> one of the ideas being a complete rewrite of the state machine. However,
> a concern was raised over the risk of regressions. The code we have has
> seen a lot of real world testing, and it would take a long time for any
> new code to get that same exposure. On top of that, there is no explicit
> igt coverage for link training since it is very dependent on the hw
> setup.
>
> Since gathering an extensive set of hardware combinations for getting the
> appropriate test coverage is really difficult, I believe that we should
> aim at testing the link training code in isolation. That's what this RFC
> is about.
>
> Most of the kernel patches in this series are small changes to the hw
> independent part of the link training code that make it possible to move
> it to a separate file. Then, in the igt patch, a test is created the
> wraps a fake DP sink device around the link training code. The behavior
> of that sink device is pretty simple for now, it just tries to get the
> maximum voltage swing and pre-emphasis level supported. We could do some
> git archeology of the link training code to try to find some more tests
> that would make sense.
>
> I had to make a lot of hacks to get that thing to compile, so that's
> one of the things I'd like to hear comments on. And also on the general
> approach.
>
> Thanks,
> Ander
>
> --
> 2.4.3
>
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--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch