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From:   Alex Deucher <alexdeucher@gmail.com>
Date:   Thu, 1 Oct 2020 10:05:15 -0400
Message-ID: <CADnq5_OOL3UZXKXEKU8VzkZAkOnk9HM8m=nEwywoQPm4GXs0rw@mail.gmail.com>
Subject: Re: BUG: amdgpu: NULL pointer dereference introduced in 5.9-rc1
To:     Dirk Gouders <dirk@gouders.net>
Cc:     Alex Deucher <alexander.deucher@amd.com>,
        Evan Quan <evan.quan@amd.com>,
        Hawking Zhang <Hawking.Zhang@amd.com>,
        =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>,
        amd-gfx list <amd-gfx@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Wed, Sep 30, 2020 at 4:46 PM Dirk Gouders <dirk@gouders.net> wrote:
>
> Commit c1cf79ca5ced46 (drm/amdgpu: use IP discovery table for renoir)
> introduced a NULL pointer dereference when booting with
> amdgpu.discovery=0.
>
> For amdgpu.discovery=0 that commit effectively removed the call of
> vega10_reg_base_init(adev), so I tested the correctness of the bisect
> session by restoring that function call for amdgpu_discovery == 0 and with
> that change, the NULL pointer dereference does not occur:
>

Can I add your Signed-off-by?

Thanks,

Alex

> diff --git a/drivers/gpu/drm/amd/amdgpu/soc15.c b/drivers/gpu/drm/amd/amdgpu/soc15.c
> index 84d811b6e48b..2e93c5e1e7e6 100644
> --- a/drivers/gpu/drm/amd/amdgpu/soc15.c
> +++ b/drivers/gpu/drm/amd/amdgpu/soc15.c
> @@ -699,7 +699,8 @@ static void soc15_reg_base_init(struct amdgpu_device *adev)
>                                          "fallback to legacy init method\n");
>                                 vega10_reg_base_init(adev);
>                         }
> -               }
> +               } else
> +                       vega10_reg_base_init(adev);
>                 break;
>         case CHIP_VEGA20:
>                 vega20_reg_base_init(adev);
>
> Dirk
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