Re: [PATCH 1/2] drm/nouveau/bar/gf100: fix hang when calling ->fini() before ->init()

[Ben Skeggs <bskeggs@xxxxxxxxxx>]

On Wed, Dec 6, 2017 at 12:30 AM, Jon Hunter <jonathanh@xxxxxxxxxx> wrote:

On 04/12/17 18:37, Guillaume Tucker wrote:
> If the firmware fails to load then ->fini() will be called before the
> device has been initialised, causing the kernel to hang while trying
> to write to a register.  Add a test in ->fini() to avoid this issue.
>
> This fixes a kernel hang on tegra124.
>
> Fixes: b17de35a2ebbe ("drm/nouveau/bar: implement bar1 teardown")
> Signed-off-by: Guillaume Tucker <guillaume.tucker@collabora.com>
> CC: Ben Skeggs <bskeggs@xxxxxxxxxx>
> ---
>  drivers/gpu/drm/nouveau/nvkm/subdev/bar/gf100.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/bar/gf100.c b/drivers/gpu/drm/nouveau/nvkm/subdev/bar/gf100.c
> index a3ba7f50198b..95e2aba64aad 100644
> --- a/drivers/gpu/drm/nouveau/nvkm/subdev/bar/gf100.c
> +++ b/drivers/gpu/drm/nouveau/nvkm/subdev/bar/gf100.c
> @@ -43,9 +43,12 @@ gf100_bar_bar1_wait(struct nvkm_bar *base)
>  }
>
>  void
> -gf100_bar_bar1_fini(struct nvkm_bar *bar)
> +gf100_bar_bar1_fini(struct nvkm_bar *base)
>  {
> -     nvkm_mask(bar->subdev.device, 0x001704, 0x80000000, 0x00000000);
> +     struct nvkm_device *device = base->subdev.device;
> +
> +     if (base->subdev.oneinit)
> +             nvkm_mask(device, 0x001704, 0x80000000, 0x00000000);
>  }
>
>  void

I have tested this and it works for me. Thanks for fixing this! Would be
good to get Ben's ACK, but you can have my ...

I'd love to get a good explanation as to why it hangs without this change, as, on the surface, it's not immediately obvious as to why it's hanging.

Thanks,

Ben.

 

Tested-by: Jon Hunter <jonathanh@xxxxxxxxxx>

Cheers
Jon

--
nvpublic

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