drm/amdgpu: reduce the time of reading VBIOS

VRAM is usually marked write combined, so change ioremap mode from
noncache to write combine for reading vbios from VRAM.

This will reduce cost time of reading vbios from 188ms to 8ms.

Signed-off-by: Xiangliang Yu <Xiangliang.Yu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
This commit is contained in:
Xiangliang Yu 2017-06-09 17:12:02 +08:00 • committed by Alex Deucher
commit f31c94d1de