drm/radeon: fixup bad vram size on SI

commit 0ca223b029a261e82fb2f50c52eb85d510f4260e upstream.

Some boards seem to have garbage in the upper
16 bits of the vram size register.  Check for
this and clamp the size properly.  Fixes
boards reporting bogus amounts of vram.

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/gpu/drm/radeon/si.c b/drivers/gpu/drm/radeon/si.c
index f054a3b6c4b86d2f81ae04f74b5d4fc97e088282..bf14a6b89b59b3795fe405606a9993bfaa5ac8b4 100644 (file)
--- a/drivers/gpu/drm/radeon/si.c
+++ b/drivers/gpu/drm/radeon/si.c
@@ -3615,8 +3615,15 @@ static int si_mc_init(struct radeon_device *rdev)
        rdev->mc.aper_base = pci_resource_start(rdev->pdev, 0);
        rdev->mc.aper_size = pci_resource_len(rdev->pdev, 0);
        /* size in MB on si */
-       rdev->mc.mc_vram_size = RREG32(CONFIG_MEMSIZE) * 1024ULL * 1024ULL;
-       rdev->mc.real_vram_size = RREG32(CONFIG_MEMSIZE) * 1024ULL * 1024ULL;
+       tmp = RREG32(CONFIG_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;
+       }
+       rdev->mc.mc_vram_size = tmp * 1024ULL * 1024ULL;
+       rdev->mc.real_vram_size = rdev->mc.mc_vram_size;
        rdev->mc.visible_vram_size = rdev->mc.aper_size;
        si_vram_gtt_location(rdev, &rdev->mc);
        radeon_update_bandwidth_info(rdev);