[PATCH 01/10] drm/amdgpu: use only the lower address space on GMC9

[Alex Deucher]

On Mon, Aug 27, 2018 at 12:56 PM Christian König
<ckoenig.leichtzumerken at gmail.com> wrote:
>
> Only use the lower address space on GMC9 for the system domain.
> Otherwise we would need to sign extend GMC addresses.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> index e44b5191735d..d982956c8329 100644
> --- a/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> +++ b/drivers/gpu/drm/amd/amdgpu/gmc_v9_0.c
> @@ -938,11 +938,10 @@ static int gmc_v9_0_sw_init(void *handle)
>         if (r)
>                 return r;
>
> -       /* Set the internal MC address mask
> -        * This is the max address of the GPU's
> -        * internal address space.
> +       /* Use only the lower range for the internal MC address mask. This is
> +        * the max address of the GPU's internal address space.
>          */

Update this comment to note the sign extension requirements and note
that this max address is only for the system context (vmid 0).  With
that fixed:
Reviewed-by: Alex Deucher <alexander.deucher at amd.com>

Alex

> -       adev->gmc.mc_mask = 0xffffffffffffULL; /* 48 bit MC */
> +       adev->gmc.mc_mask = 0x7fffffffffffULL;
>
>         /* set DMA mask + need_dma32 flags.
>          * PCIE - can handle 44-bits.
> --
> 2.17.1
>
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