drm/nouveau/dp: fix required link bandwidth calculations

Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

3 files changed, 11 insertions, 9 deletions

diff --git a/drivers/gpu/drm/nouveau/core/engine/disp/nv50.c b/drivers/gpu/drm/nouveau/core/engine/disp/nv50.c
index 26e962b7e702..2283c442a10d 100644
--- a/drivers/gpu/drm/nouveau/core/engine/disp/nv50.c
+++ b/drivers/gpu/drm/nouveau/core/engine/disp/nv50.c
@@ -1516,11 +1516,11 @@ nv50_disp_intr_unk20_2(struct nv50_disp_priv *priv, int head)
                 }
 
                 switch ((ctrl & 0x000f0000) >> 16) {
-                case 6: datarate = pclk * 30 / 8; break;
-                case 5: datarate = pclk * 24 / 8; break;
+                case 6: datarate = pclk * 30; break;
+                case 5: datarate = pclk * 24; break;
                 case 2:
                 default:
-                        datarate = pclk * 18 / 8;
+                        datarate = pclk * 18;
                         break;
                 }
 
diff --git a/drivers/gpu/drm/nouveau/core/engine/disp/nvd0.c b/drivers/gpu/drm/nouveau/core/engine/disp/nvd0.c
index 48aa38a87e3f..fa30d8196f35 100644
--- a/drivers/gpu/drm/nouveau/core/engine/disp/nvd0.c
+++ b/drivers/gpu/drm/nouveau/core/engine/disp/nvd0.c
@@ -1159,11 +1159,11 @@ nvd0_disp_intr_unk2_2(struct nv50_disp_priv *priv, int head)
         if (outp->info.type == DCB_OUTPUT_DP) {
                 u32 sync = nv_rd32(priv, 0x660404 + (head * 0x300));
                 switch ((sync & 0x000003c0) >> 6) {
-                case 6: pclk = pclk * 30 / 8; break;
-                case 5: pclk = pclk * 24 / 8; break;
+                case 6: pclk = pclk * 30; break;
+                case 5: pclk = pclk * 24; break;
                 case 2:
                 default:
-                        pclk = pclk * 18 / 8;
+                        pclk = pclk * 18;
                         break;
                 }
 
diff --git a/drivers/gpu/drm/nouveau/core/engine/disp/outpdp.c b/drivers/gpu/drm/nouveau/core/engine/disp/outpdp.c
index 52c299c3d300..eb2d7789555d 100644
--- a/drivers/gpu/drm/nouveau/core/engine/disp/outpdp.c
+++ b/drivers/gpu/drm/nouveau/core/engine/disp/outpdp.c
@@ -34,7 +34,7 @@ nvkm_output_dp_train(struct nvkm_output *base, u32 datarate, bool wait)
         struct nvkm_output_dp *outp = (void *)base;
         bool retrain = true;
         u8 link[2], stat[3];
-        u32 rate;
+        u32 linkrate;
         int ret, i;
 
         /* check that the link is trained at a high enough rate */
@@ -44,8 +44,10 @@ nvkm_output_dp_train(struct nvkm_output *base, u32 datarate, bool wait)
                 goto done;
         }
 
-        rate = link[0] * 27000 * (link[1] & DPCD_LC01_LANE_COUNT_SET);
-        if (rate < ((datarate / 8) * 10)) {
+        linkrate = link[0] * 27000 * (link[1] & DPCD_LC01_LANE_COUNT_SET);
+        linkrate = (linkrate * 8) / 10; /* 8B/10B coding overhead */
+        datarate = (datarate + 9) / 10; /* -> decakilobits */
+        if (linkrate < datarate) {
                 DBG("link not trained at sufficient rate\n");
                 goto done;
         }