[PATCH] drm/amd/display: fix the white screen issue when >= 64GB DRAM

[Christian König]

Am 08.09.23 um 10:46 schrieb Yifan Zhang:
> dropping bit 31:4 of paget table base is wrong, it makes page table
> base points to wrong address if phys addr is beyond 64GB; dropping
> page_table_start/end bit 31:4 is unnecessary since dcn20_vmid_setup
> will do that.
>
> Signed-off-by: Yifan Zhang <yifan1.zhang at amd.com>

Good catch, one nit pick below.

With out without that Acked-by: Christian König <christian.koenig at amd.com>

> ---
>   drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> index 1bb1a394f55f..f8bf04fcceac 100644
> --- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> +++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
> @@ -1283,11 +1283,11 @@ static void mmhub_read_system_context(struct amdgpu_device *adev, struct dc_phy_
>   
>   	pt_base = amdgpu_gmc_pd_addr(adev->gart.bo);
>   
> -	page_table_start.high_part = (u32)(adev->gmc.gart_start >> 44) & 0xF;
> +	page_table_start.high_part = (u32)(adev->gmc.gart_start >> 44);
>   	page_table_start.low_part = (u32)(adev->gmc.gart_start >> 12);
> -	page_table_end.high_part = (u32)(adev->gmc.gart_end >> 44) & 0xF;
> +	page_table_end.high_part = (u32)(adev->gmc.gart_end >> 44);
>   	page_table_end.low_part = (u32)(adev->gmc.gart_end >> 12);

While at it you might want to change those to use AMDGPU_GPU_PAGE_SHIFT 
and the lower_32_bits() and upper_32_bits() functions instead.

Something like:

page_table_end.high_part = upper_32_bits(adev->gmc.gart_end >> 
AMDGPU_GPU_PAGE_SHIFT);
page_table_end.low_part = lower_32_bits(adev->gmc.gart_end >> 
AMDGPU_GPU_PAGE_SHIFT);

Not a must have, but might be a bit cleaner.

Regards,
Christian.

> -	page_table_base.high_part = upper_32_bits(pt_base) & 0xF;
> +	page_table_base.high_part = upper_32_bits(pt_base);
>   	page_table_base.low_part = lower_32_bits(pt_base);
>   
>   	pa_config->system_aperture.start_addr = (uint64_t)logical_addr_low << 18;