drm/amdgpu: Enable scatter gather display support

Enables sg display if vram size <= THRESHOLD(256M); otherwise
still use vram as display buffer.
This patch fixed some potention issues introduced by change
"allow framebuffer in GART memory as well" due to CZ/ST hardware
limitation.

v2: Change default setting to auto.
v3: Move some logic from amdgpu_display_framebuffer_domains()
    to pin function, suggested by Christian.
v4: Split into several patches.
v5: Drop module parameter for now.

Signed-off-by: Samuel Li <Samuel.Li@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
index 7570055..03a2c0b 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
@@ -138,6 +138,7 @@ extern int amdgpu_si_support;
 extern int amdgpu_cik_support;
 #endif
 
+#define AMDGPU_SG_THRESHOLD                    (256*1024*1024)
 #define AMDGPU_DEFAULT_GTT_SIZE_MB             3072ULL /* 3GB by default */
 #define AMDGPU_WAIT_IDLE_TIMEOUT_IN_MS         3000
 #define AMDGPU_MAX_USEC_TIMEOUT                        100000  /* 100 ms */

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
index 1985c08..e62153a 100644 (file)
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_object.c
@@ -701,6 +701,15 @@ int amdgpu_bo_pin_restricted(struct amdgpu_bo *bo, u32 domain,
                        return -EINVAL;
        }
 
+       /* This assumes only APU display buffers are pinned with (VRAM|GTT).
+        * See function amdgpu_display_supported_domains()
+        */
+       if (domain == (AMDGPU_GEM_DOMAIN_VRAM | AMDGPU_GEM_DOMAIN_GTT)) {
+               domain = AMDGPU_GEM_DOMAIN_VRAM;
+               if (adev->gmc.real_vram_size <= AMDGPU_SG_THRESHOLD)
+                       domain = AMDGPU_GEM_DOMAIN_GTT;
+       }
+
        if (bo->pin_count) {
                uint32_t mem_type = bo->tbo.mem.mem_type;