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>

diff --git a/drivers/gpu/drm/nouveau/core/engine/disp/dport.c b/drivers/gpu/drm/nouveau/core/engine/disp/dport.c
index c2bf611..39562d4 100644 (file)
--- 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);