[Nouveau] [PATCH 3/3] drm/nv50: wait for pgraph to idle before unloading the context

[Ben Skeggs]

On Mon, 2010-01-11 at 22:12 +0100, Maarten Maathuis wrote:
> A few comments are in order, i noticed that this additional
> wait_for_idle does cause delays sometimes (obviously). and it seems
> like an excellent way to do a DOS attack on your gpu. fbcon is visibly
> lagging sometimes and even unusable (gpu is not locked up,  X works
> fine started from ssh). This seems like something to consider when
> choosing the preferred solution.
Yeah, I think the wait_for_idle() is fine.  I'm actually interested it
solved the problem completely for you, as I mentioned to you (maybe?), I
still seen an *occasional* hang when I tried it.  But, it's still a huge
improvement over now.

Ben.
> 
> On Mon, Jan 11, 2010 at 9:22 PM, Maarten Maathuis <madman2003 at gmail.com> wrote:
> > This patch *is* alone, sorry for the typo.
> >
> > On Mon, Jan 11, 2010 at 9:20 PM, Maarten Maathuis <madman2003 at gmail.com> wrote:
> >> This patch alone, so ignore the 3/3. I think this fixes the channel
> >> unload hang issues in a less obscure way. Feedback appreciated as
> >> usual.
> >>
> >> On Mon, Jan 11, 2010 at 9:18 PM, Maarten Maathuis <madman2003 at gmail.com> wrote:
> >>> - This should fix the problem with gpu hangs people have had when closing
> >>> channels.
> >>>
> >>> Signed-off-by: Maarten Maathuis <madman2003 at gmail.com>
> >>> ---
> >>>  drivers/gpu/drm/nouveau/nv50_graph.c |    1 +
> >>>  1 files changed, 1 insertions(+), 0 deletions(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/nouveau/nv50_graph.c b/drivers/gpu/drm/nouveau/nv50_graph.c
> >>> index 444a46b..d6897cf 100644
> >>> --- a/drivers/gpu/drm/nouveau/nv50_graph.c
> >>> +++ b/drivers/gpu/drm/nouveau/nv50_graph.c
> >>> @@ -282,6 +282,7 @@ nv50_graph_unload_context(struct drm_device *dev)
> >>>                return 0;
> >>>        inst &= NV50_PGRAPH_CTXCTL_CUR_INSTANCE;
> >>>
> >>> +       nouveau_wait_for_idle(dev);
> >>>        nv_wr32(dev, 0x400500, fifo & ~1);
> >>>        nv_wr32(dev, 0x400784, inst);
> >>>        nv_wr32(dev, 0x400824, nv_rd32(dev, 0x400824) | 0x20);
> >>> --
> >>> 1.6.6
> >>>
> >>>
> >>
> >
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