From bcc05372a2c226ad61472b7a72c72aeba9584980 Mon Sep 17 00:00:00 2001
From: Marek Vasut <marex@denx.de>
Date: Fri, 20 May 2022 14:15:43 +0200
Subject: [PATCH] drm/bridge: tc358767: Make sure Refclk clock are enabled

[ Upstream commit 0b4c48f3e315d172e4cc06e10f2c8ba180788baf ]

The Refclk may be supplied by SoC clock output instead of crystal
oscillator, make sure the clock are enabled before any other action
is performed with the bridge chip, otherwise it may either fail to
operate at all, or miss reset GPIO toggle.

Reviewed-by: Lucas Stach <l.stach@pengutronix.de>
Fixes: 7caff0fc4296e ("drm/bridge: tc358767: Add DPI to eDP bridge driver")
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Jonas Karlman <jonas@kwiboo.se>
Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Marek Vasut <marex@denx.de>
Cc: Maxime Ripard <maxime@cerno.tech>
Cc: Neil Armstrong <narmstrong@baylibre.com>
Cc: Robert Foss <robert.foss@linaro.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Reviewed-by: Maxime Ripard <maxime@cerno.tech>
Link: https://patchwork.freedesktop.org/patch/msgid/20220520121543.11550-1-marex@denx.de
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/gpu/drm/bridge/tc358767.c | 32 ++++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c
index 9af564cf92e5..3e365cd7d0a3 100644
--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -1562,6 +1562,13 @@ static int tc_probe_edp_bridge_endpoint(struct tc_data *tc)
 	return ret;
 }
 
+static void tc_clk_disable(void *data)
+{
+	struct clk *refclk = data;
+
+	clk_disable_unprepare(refclk);
+}
+
 static int tc_probe(struct i2c_client *client, const struct i2c_device_id *id)
 {
 	struct device *dev = &client->dev;
@@ -1578,6 +1585,24 @@ static int tc_probe(struct i2c_client *client, const struct i2c_device_id *id)
 	if (ret)
 		return ret;
 
+	tc->refclk = devm_clk_get(dev, "ref");
+	if (IS_ERR(tc->refclk)) {
+		ret = PTR_ERR(tc->refclk);
+		dev_err(dev, "Failed to get refclk: %d\n", ret);
+		return ret;
+	}
+
+	ret = clk_prepare_enable(tc->refclk);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action_or_reset(dev, tc_clk_disable, tc->refclk);
+	if (ret)
+		return ret;
+
+	/* tRSTW = 100 cycles , at 13 MHz that is ~7.69 us */
+	usleep_range(10, 15);
+
 	/* Shut down GPIO is optional */
 	tc->sd_gpio = devm_gpiod_get_optional(dev, "shutdown", GPIOD_OUT_HIGH);
 	if (IS_ERR(tc->sd_gpio))
@@ -1598,13 +1623,6 @@ static int tc_probe(struct i2c_client *client, const struct i2c_device_id *id)
 		usleep_range(5000, 10000);
 	}
 
-	tc->refclk = devm_clk_get(dev, "ref");
-	if (IS_ERR(tc->refclk)) {
-		ret = PTR_ERR(tc->refclk);
-		dev_err(dev, "Failed to get refclk: %d\n", ret);
-		return ret;
-	}
-
 	tc->regmap = devm_regmap_init_i2c(client, &tc_regmap_config);
 	if (IS_ERR(tc->regmap)) {
 		ret = PTR_ERR(tc->regmap);