drm/bridge: tc358767: fix ansi 8b10b use

DP always uses ANSI 8B10B encoding. Some monitors (old?) may not have
the ANSI 8B10B bit set in DPCD, even if it should always be set.

The tc358767 driver currently respects that flag, and turns the encoding
off if the monitor does not have the bit set, which then results in the
monitor not working.

This patch makes the driver to always use ANSI 8B10B encoding, and drops
the 'coding8b10b' field which is no longer used.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Reviewed-by: Andrzej Hajda <a.hajda@samsung.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190528082747.3631-4-tomi.valkeinen@ti.com

drivers/gpu/drm/bridge/tc358767.c

@@ -188,7 +188,6 @@ struct tc_edp_link {
 	u8			assr;
 	int			scrambler_dis;
 	int			spread;
-	int			coding8b10b;
 	u8			swing;
 	u8			preemp;
 };
@@ -390,13 +389,10 @@ static u32 tc_srcctrl(struct tc_data *tc)
 	 * No training pattern, skew lane 1 data by two LSCLK cycles with
 	 * respect to lane 0 data, AutoCorrect Mode = 0
 	 */
-	u32 reg = DP0_SRCCTRL_NOTP | DP0_SRCCTRL_LANESKEW;
+	u32 reg = DP0_SRCCTRL_NOTP | DP0_SRCCTRL_LANESKEW | DP0_SRCCTRL_EN810B;
 
 	if (tc->link.scrambler_dis)
 		reg |= DP0_SRCCTRL_SCRMBLDIS;	/* Scrambler Disabled */
-	if (tc->link.coding8b10b)
-		/* Enable 8/10B Encoder (TxData[19:16] not used) */
-		reg |= DP0_SRCCTRL_EN810B;
 	if (tc->link.spread)
 		reg |= DP0_SRCCTRL_SSCG;	/* Spread Spectrum Enable */
 	if (tc->link.base.num_lanes == 2)
@@ -635,7 +631,7 @@ static int tc_get_display_props(struct tc_data *tc)
 	ret = drm_dp_dpcd_readb(&tc->aux, DP_MAIN_LINK_CHANNEL_CODING, tmp);
 	if (ret < 0)
 		goto err_dpcd_read;
-	tc->link.coding8b10b = tmp[0] & BIT(0);
+
 	tc->link.scrambler_dis = 0;
 	/* read assr */
 	ret = drm_dp_dpcd_readb(&tc->aux, DP_EDP_CONFIGURATION_SET, tmp);
@@ -649,7 +645,6 @@ static int tc_get_display_props(struct tc_data *tc)
 		tc->link.base.num_lanes,
 		(tc->link.base.capabilities & DP_LINK_CAP_ENHANCED_FRAMING) ?
 		"enhanced" : "non-enhanced");
-	dev_dbg(tc->dev, "ANSI 8B/10B: %d\n", tc->link.coding8b10b);
 	dev_dbg(tc->dev, "Display ASSR: %d, TC358767 ASSR: %d\n",
 		tc->link.assr, tc->assr);
 
@@ -951,7 +946,7 @@ static int tc_main_link_setup(struct tc_data *tc)
 	/* DOWNSPREAD_CTRL */
 	tmp[0] = tc->link.spread ? DP_SPREAD_AMP_0_5 : 0x00;
 	/* MAIN_LINK_CHANNEL_CODING_SET */
-	tmp[1] =  tc->link.coding8b10b ? DP_SET_ANSI_8B10B : 0x00;
+	tmp[1] =  DP_SET_ANSI_8B10B;
 	ret = drm_dp_dpcd_write(aux, DP_DOWNSPREAD_CTRL, tmp, 2);
 	if (ret < 0)
 		goto err_dpcd_write;