Re: [Nouveau] [PATCH] drm/nouveau/bar/gk20a: Avoid bar teardown during init

[Guillaume Tucker]

On 10/01/18 12:20, Thierry Reding wrote:
> On Thu, Jan 04, 2018 at 11:29:09AM +0000, Jon Hunter wrote:
> > Commit bbb163e18960 ("drm/nouveau/bar: implement bar1 teardown")
> > introduced add a teardown helper function for BAR1. During
> > initialisation of the Nouveau, initially all the teardown helpers are
> > called once, before calling their init counterparts. For gk20a, after
> > the BAR1 teardown function is called, the device is hanging during the
> > initialisation of the FB sub-device. At this point it is unclear why
> > this is happening and this is still under investigation. However, this
> > change is preventing Tegra124 devices from booting when Nouveau is
> > enabled. To allow Tegra124 to boot, remove the teardown helper for
> > gk20a.
> >
> > This is based upon a previous patch by Guillaume Tucker but limits
> > the workaround to only gk20a GPUs.
> >
> > Fixes: bbb163e18960 ("drm/nouveau/bar: implement bar1 teardown")
> > Reported-by: Guillaume Tucker <guillaume.tucker@xxxxxxxxxxxxx>
> > Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx>
> > ---
> > I am not happy that we do not yet fully understand the cause of
> > the hang, but I am talking with a few people at NVIDIA about this
> > and have a few things to look into. However, given that we are
> > close to v4.15 being released and I am not sure we will have a
> > proper fix in place before, I think it is best to workaround
> > this for now.
> >
> >   drivers/gpu/drm/nouveau/nvkm/subdev/bar/base.c  | 3 ++-
> >   drivers/gpu/drm/nouveau/nvkm/subdev/bar/gk20a.c | 1 -
> >   2 files changed, 2 insertions(+), 2 deletions(-)
>
> Acked-by: Thierry Reding <treding@xxxxxxxxxx>

Tested-by: Guillaume Tucker <guillaume.tucker@xxxxxxxxxxxxx>

  https://lava.collabora.co.uk/scheduler/job/1047172

Thanks for this workaround.  Looking forward to having this
platform back on track in mainline.  I'm happy to run this boot
test again with a proper fix in future patches, let me know if I
can be of any help.

Guillaume