drm/nouveau/disp/dp: make use of postcursor when its available

And at the same time, obey the spec better wrt out-of-range requests.

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

1 files changed, 18 insertions, 8 deletions

diff --git a/drivers/gpu/drm/nouveau/core/engine/disp/dport.c b/drivers/gpu/drm/nouveau/core/engine/disp/dport.c
index c2bf611db593..39562d48101d 100644
--- a/drivers/gpu/drm/nouveau/core/engine/disp/dport.c
+++ b/drivers/gpu/drm/nouveau/core/engine/disp/dport.c
@@ -130,18 +130,28 @@ dp_link_train_commit(struct dp_state *dp, bool pc)
 
         for (i = 0; i < dp->link_nr; i++) {
                 u8 lane = (dp->stat[4 + (i >> 1)] >> ((i & 1) * 4)) & 0xf;
+                u8 lpc2 = (dp->pc2stat >> (i * 2)) & 0x3;
                 u8 lpre = (lane & 0x0c) >> 2;
                 u8 lvsw = (lane & 0x03) >> 0;
+                u8 hivs = 3 - lpre;
+                u8 hipe = 3;
+                u8 hipc = 3;
+
+                if (lpc2 >= hipc)
+                        lpc2 = hipc | DPCD_LC0F_LANE0_MAX_POST_CURSOR2_REACHED;
+                if (lpre >= hipe) {
+                        lpre = hipe | DPCD_LC03_MAX_SWING_REACHED; /* yes. */
+                        lvsw = hivs = 3 - (lpre & 3);
+                } else
+                if (lvsw >= hivs) {
+                        lvsw = hivs | DPCD_LC03_MAX_SWING_REACHED;
+                }
 
                 dp->conf[i] = (lpre << 3) | lvsw;
-                if (lvsw == 3)
-                        dp->conf[i] |= DPCD_LC03_MAX_SWING_REACHED;
-                if (lpre == 3)
-                        dp->conf[i] |= DPCD_LC03_MAX_PRE_EMPHASIS_REACHED;
-                dp->pc2conf[i >> 1] |= 4 << ((i & 1) * 4);
-
-                DBG("config lane %d %02x\n", i, dp->conf[i]);
-                impl->drv_ctl(outp, i, lvsw, lpre, 0);
+                dp->pc2conf[i >> 1] |= lpc2 << ((i & 1) * 4);
+
+                DBG("config lane %d %02x %02x\n", i, dp->conf[i], lpc2);
+                impl->drv_ctl(outp, i, lvsw & 3, lpre & 3, lpc2 & 3);
         }
 
         ret = nv_wraux(outp->base.edid, DPCD_LC03(0), dp->conf, 4);