drm/amdgpu/gmc: steal the appropriate amount of vram for fw hand-over (v3)

Steal 9 MB for vga emulation and fb if vga is enabled, otherwise,
steal enough to cover the current display size as set by the vbios.

If no memory is used (e.g., secondary or headless card), skip
stolen memory reserve.

v2: skip reservation if vram is limited, address Christian's comments
v3: squash in fix from Harry

Reviewed-and-Tested-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com> (v2)
Signed-off-by: Alex Deucher <alexdeucher@gmail.com>

1 files changed, 21 insertions, 2 deletions

diff --git a/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c b/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c
index 5617cf62c566..24e1ea36b454 100644
--- a/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c
+++ b/drivers/gpu/drm/amd/amdgpu/gmc_v6_0.c
@@ -825,6 +825,25 @@ static int gmc_v6_0_late_init(void *handle)
 		return 0;
 }
 
+static unsigned gmc_v6_0_get_vbios_fb_size(struct amdgpu_device *adev)
+{
+	u32 d1vga_control = RREG32(mmD1VGA_CONTROL);
+	unsigned size;
+
+	if (REG_GET_FIELD(d1vga_control, D1VGA_CONTROL, D1VGA_MODE_ENABLE)) {
+		size = 9 * 1024 * 1024; /* reserve 8MB for vga emulator and 1 MB for FB */
+	} else {
+		u32 viewport = RREG32(mmVIEWPORT_SIZE);
+		size = (REG_GET_FIELD(viewport, VIEWPORT_SIZE, VIEWPORT_HEIGHT) *
+			REG_GET_FIELD(viewport, VIEWPORT_SIZE, VIEWPORT_WIDTH) *
+			4);
+	}
+	/* return 0 if the pre-OS buffer uses up most of vram */
+	if ((adev->gmc.real_vram_size - size) < (8 * 1024 * 1024))
+		return 0;
+	return size;
+}
+
 static int gmc_v6_0_sw_init(void *handle)
 {
 	int r;
@@ -851,8 +870,6 @@ static int gmc_v6_0_sw_init(void *handle)
 
 	adev->gmc.mc_mask = 0xffffffffffULL;
 
-	adev->gmc.stolen_size = 256 * 1024;
-
 	adev->need_dma32 = false;
 	dma_bits = adev->need_dma32 ? 32 : 40;
 	r = pci_set_dma_mask(adev->pdev, DMA_BIT_MASK(dma_bits));
@@ -878,6 +895,8 @@ static int gmc_v6_0_sw_init(void *handle)
 	if (r)
 		return r;
 
+	adev->gmc.stolen_size = gmc_v6_0_get_vbios_fb_size(adev);
+
 	r = amdgpu_bo_init(adev);
 	if (r)
 		return r;