drm/nouveau/disp: limit dp capabilities as per dcb

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

2 files changed, 36 insertions, 1 deletions

diff --git a/drivers/gpu/drm/nouveau/core/engine/disp/dport.c b/drivers/gpu/drm/nouveau/core/engine/disp/dport.c
index 1bd4c63369c1..2aedb4e47d03 100644
--- a/drivers/gpu/drm/nouveau/core/engine/disp/dport.c
+++ b/drivers/gpu/drm/nouveau/core/engine/disp/dport.c
@@ -312,6 +312,14 @@ nouveau_dp_train(struct nouveau_disp *disp, const struct nouveau_dp_func *func,
                 ERR("failed to read DPCD\n");
         }
 
+        /* bring capabilities within encoder limits */
+        if ((dp->dpcd[2] & 0x1f) > dp->outp->dpconf.link_nr) {
+                dp->dpcd[2] &= ~0x1f;
+                dp->dpcd[2] |= dp->outp->dpconf.link_nr;
+        }
+        if (dp->dpcd[1] > dp->outp->dpconf.link_bw)
+                dp->dpcd[1] = dp->outp->dpconf.link_bw;
+
         /* adjust required bandwidth for 8B/10B coding overhead */
         datarate = (datarate / 8) * 10;
 
diff --git a/drivers/gpu/drm/nouveau/core/subdev/bios/dcb.c b/drivers/gpu/drm/nouveau/core/subdev/bios/dcb.c
index 2d9b9d7a7992..88606bfaf847 100644
--- a/drivers/gpu/drm/nouveau/core/subdev/bios/dcb.c
+++ b/drivers/gpu/drm/nouveau/core/subdev/bios/dcb.c
@@ -142,9 +142,36 @@ dcb_outp_parse(struct nouveau_bios *bios, u8 idx, u8 *ver, u8 *len,
                 if (*ver >= 0x40) {
                         u32 conf = nv_ro32(bios, dcb + 0x04);
                         switch (outp->type) {
+                        case DCB_OUTPUT_DP:
+                                switch (conf & 0x00e00000) {
+                                case 0x00000000:
+                                        outp->dpconf.link_bw = 0x06;
+                                        break;
+                                case 0x00200000:
+                                        outp->dpconf.link_bw = 0x0a;
+                                        break;
+                                case 0x00400000:
+                                default:
+                                        outp->dpconf.link_bw = 0x14;
+                                        break;
+                                }
+
+                                switch (conf & 0x0f000000) {
+                                case 0x0f000000:
+                                        outp->dpconf.link_nr = 4;
+                                        break;
+                                case 0x03000000:
+                                        outp->dpconf.link_nr = 2;
+                                        break;
+                                case 0x01000000:
+                                default:
+                                        outp->dpconf.link_nr = 1;
+                                        break;
+                                }
+
+                                /* fall-through... */
                         case DCB_OUTPUT_TMDS:
                         case DCB_OUTPUT_LVDS:
-                        case DCB_OUTPUT_DP:
                                 outp->link = (conf & 0x00000030) >> 4;
                                 outp->sorconf.link = outp->link; /*XXX*/
                                 outp->extdev = 0x00;