[PATCH v2 3/3] drm/nouveau: Add drm_panic support for nv50+

[Ilia Mirkin]

On Fri, Sep 6, 2024 at 9:10 AM Jocelyn Falempe <jfalempe at redhat.com> wrote:

> On 06/09/2024 14:53, Ilia Mirkin wrote:
> > On Fri, Sep 6, 2024 at 6:05 AM Jocelyn Falempe <jfalempe at redhat.com
> > <mailto:jfalempe at redhat.com>> wrote:
> >
> >     Add drm_panic support, for nv50+ cards.
> >     It's enough to get the panic screen while running Gnome/Wayland on a
> >     GTX 1650.
> >     It doesn't support multi-plane or compressed format.
> >     Support for other formats and older cards will come later.
> >     Tiling is only tested on GTX1650, and might be wrong for other cards.
> >
> >
> > I'm moderately sure that nv50 and nvc0 tile differently (the general
> > algo is the same, but height is different):
> >
> >
> https://envytools.readthedocs.io/en/latest/hw/memory/g80-surface.html?highlight=tiling#blocklinear-surfaces
> <
> https://envytools.readthedocs.io/en/latest/hw/memory/g80-surface.html?highlight=tiling#blocklinear-surfaces
> >
>
> Thanks, it looks like it needs a small adjustment, as in the Doc, GF100
> uses a default height of 4, and GF100+ default to 8 (and I've hardcoded
> it to NV_TILE_BLK_BASE_HEIGHT 8).
> GF100 is still nv50, so it should use this code.
>

Just as a point of clarification -- nv50 = G80. nvc0 = GF100. (There are
many other chips, but those are the big generational changes as far as this
code is concerned. https://nouveau.freedesktop.org/CodeNames.html for a
fuller list.)


>
> >
> > That said, I don't know that nv50 supports scanout of tiled surfaces
> > (nor was I aware that nvc0+ did, perhaps it's a recent feature, or
> > perhaps I'm just forgetful).
>
> What I know is that when using Gnome/Wayland, the framebuffer is tiled,
> and without this tiling code, the panic screen is unreadable.
> When using the VT console, the framebuffer is linear, and it's easier.
>

OK. Then clearly it's supported :) I'm sure Ben or Lyude will know offhand
when this support came in.

Cheers,

  -ilia
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