On Wed, Dec 13, 2023 at 07:43:57PM -0500, Lyude Paul wrote:
> Turns out we made a silly mistake when coming up with OR inheritance on
> nouveau. On pre-DCB 4.1, iors are statically routed to output paths via the
> DCB. On later generations iors are only routed to an output path if they're
> actually being used. Unfortunately, it appears with NVIF_OUTP_INHERIT_V0 we
> make the mistake of assuming the later is true on all generations, which is
> currently leading us to return bogus ior -> head assignments through nvif,
> which causes WARN_ON().
>
> So - fix this by verifying that we actually know that there's a head
> assigned to an ior before allowing it to be inherited through nvif. This
> -should- hopefully fix the WARN_ON on GT218 reported by Borislav.
>
> Signed-off-by: Lyude Paul <lyude@xxxxxxxxxx>
> Cc: Borislav Petkov <bp@xxxxxxxxx>
> ---
> drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c b/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c
> index e4279f1772a1b..377d0e0cef848 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/engine/disp/uoutp.c
> @@ -385,7 +385,7 @@ nvkm_uoutp_mthd_inherit(struct nvkm_outp *outp, void *argv, u32 argc)
>
> /* Ensure an ior is hooked up to this outp already */
> ior = outp->func->inherit(outp);
> - if (!ior)
> + if (!ior || !ior->arm.head)
> return -ENODEV;
>
> /* With iors, there will be a separate output path for each type of connector - and all of
> --
Thanks, that fixes it!
Reported-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
Tested-by: Borislav Petkov (AMD) <bp@xxxxxxxxx>
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
