diff options
| -rw-r--r-- | drivers/gpu/drm/nouveau/dispnv50/disp.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c index 1a06c165a8df..5691dfa1db6f 100644 --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c @@ -1123,17 +1123,21 @@ nv50_mstm_enable(struct nv50_mstm *mstm, u8 dpcd, int state) int ret; if (dpcd >= 0x12) { - ret = drm_dp_dpcd_readb(mstm->mgr.aux, DP_MSTM_CTRL, &dpcd); + /* Even if we're enabling MST, start with disabling the + * branching unit to clear any sink-side MST topology state + * that wasn't set by us + */ + ret = drm_dp_dpcd_writeb(mstm->mgr.aux, DP_MSTM_CTRL, 0); if (ret < 0) return ret; - dpcd &= ~DP_MST_EN; - if (state) - dpcd |= DP_MST_EN; - - ret = drm_dp_dpcd_writeb(mstm->mgr.aux, DP_MSTM_CTRL, dpcd); - if (ret < 0) - return ret; + if (state) { + /* Now, start initializing */ + ret = drm_dp_dpcd_writeb(mstm->mgr.aux, DP_MSTM_CTRL, + DP_MST_EN); + if (ret < 0) + return ret; + } } return nvif_mthd(disp, 0, &args, sizeof(args)); |