drm/nv50: fail auxch transaction if reply count not what we expect

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

drivers/gpu/drm/nouveau/nouveau_dp.c

@@ -490,7 +490,8 @@ nouveau_dp_auxch(struct nouveau_i2c_chan *auxch, int cmd, int addr,
 		if (!nv_wait(NV50_AUXCH_CTRL(index), 0x00010000, 0x00000000)) {
 			NV_ERROR(dev, "expected bit 16 == 0, got 0x%08x\n",
 				 nv_rd32(dev, NV50_AUXCH_CTRL(index)));
-			return -EBUSY;
+			ret = -EBUSY;
+			goto out;
 		}
 
 		udelay(400);
@@ -501,6 +502,11 @@ nouveau_dp_auxch(struct nouveau_i2c_chan *auxch, int cmd, int addr,
 			break;
 	}
 
+	if ((stat & NV50_AUXCH_STAT_COUNT) != data_nr) {
+		ret = -EREMOTEIO;
+		goto out;
+	}
+
 	if (cmd & 1) {
 		for (i = 0; i < 4; i++) {
 			data32[i] = nv_rd32(dev, NV50_AUXCH_DATA_IN(index, i));