drm/radeon/kms: fix vram_width calculation on r6xx/r7xx

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

1 files changed, 26 insertions, 4 deletions

diff --git a/drivers/gpu/drm/radeon/rv770.c b/drivers/gpu/drm/radeon/rv770.c
index 595ac638039d..40553913b928 100644
--- a/drivers/gpu/drm/radeon/rv770.c
+++ b/drivers/gpu/drm/radeon/rv770.c
@@ -774,14 +774,36 @@ int rv770_mc_init(struct radeon_device *rdev)
 {
         fixed20_12 a;
         u32 tmp;
+        int chansize, numchan;
         int r;
 
         /* Get VRAM informations */
-        /* FIXME: Don't know how to determine vram width, need to check
-         * vram_width usage
-         */
-        rdev->mc.vram_width = 128;
         rdev->mc.vram_is_ddr = true;
+        tmp = RREG32(MC_ARB_RAMCFG);
+        if (tmp & CHANSIZE_OVERRIDE) {
+                chansize = 16;
+        } else if (tmp & CHANSIZE_MASK) {
+                chansize = 64;
+        } else {
+                chansize = 32;
+        }
+        tmp = RREG32(MC_SHARED_CHMAP);
+        switch ((tmp & NOOFCHAN_MASK) >> NOOFCHAN_SHIFT) {
+        case 0:
+        default:
+                numchan = 1;
+                break;
+        case 1:
+                numchan = 2;
+                break;
+        case 2:
+                numchan = 4;
+                break;
+        case 3:
+                numchan = 8;
+                break;
+        }
+        rdev->mc.vram_width = numchan * chansize;
         /* Could aper size report 0 ? */
         rdev->mc.aper_base = drm_get_resource_start(rdev->ddev, 0);
         rdev->mc.aper_size = drm_get_resource_len(rdev->ddev, 0);