drm/amdgpu: fixup bad vram size on gmc v8

From Zongmin Zhou
493b87970061f044c5cf795cfd1d679d114844ed in linux 5.15.y/5.15.17
11544d77e3974924c5a9c8a8320b996a3e9b2f8b in mainline linux

diff --git a/sys/dev/pci/drm/amd/amdgpu/gmc_v8_0.c b/sys/dev/pci/drm/amd/amdgpu/gmc_v8_0.c
index 339ffd9..587206d 100644 (file)
--- a/sys/dev/pci/drm/amd/amdgpu/gmc_v8_0.c
+++ b/sys/dev/pci/drm/amd/amdgpu/gmc_v8_0.c
@@ -515,10 +515,10 @@ static void gmc_v8_0_mc_program(struct amdgpu_device *adev)
 static int gmc_v8_0_mc_init(struct amdgpu_device *adev)
 {
        int r;
+       u32 tmp;
 
        adev->gmc.vram_width = amdgpu_atombios_get_vram_width(adev);
        if (!adev->gmc.vram_width) {
-               u32 tmp;
                int chansize, numchan;
 
                /* Get VRAM informations */
@@ -562,8 +562,15 @@ static int gmc_v8_0_mc_init(struct amdgpu_device *adev)
                adev->gmc.vram_width = numchan * chansize;
        }
        /* size in MB on si */
-       adev->gmc.mc_vram_size = RREG32(mmCONFIG_MEMSIZE) * 1024ULL * 1024ULL;
-       adev->gmc.real_vram_size = RREG32(mmCONFIG_MEMSIZE) * 1024ULL * 1024ULL;
+       tmp = RREG32(mmCONFIG_MEMSIZE);
+       /* some boards may have garbage in the upper 16 bits */
+       if (tmp & 0xffff0000) {
+               DRM_INFO("Probable bad vram size: 0x%08x\n", tmp);
+               if (tmp & 0xffff)
+                       tmp &= 0xffff;
+       }
+       adev->gmc.mc_vram_size = tmp * 1024ULL * 1024ULL;
+       adev->gmc.real_vram_size = adev->gmc.mc_vram_size;
 
        if (!(adev->flags & AMD_IS_APU)) {
                r = amdgpu_device_resize_fb_bar(adev);