From 0b4c48f3e315d172e4cc06e10f2c8ba180788baf 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
Git-commit: 0b4c48f3e315d172e4cc06e10f2c8ba180788baf
Patch-mainline: v6.0-rc1
References: git-fixes

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
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/bridge/tc358767.c |   32 +++++++++++++++++++++++++-------
 1 file changed, 25 insertions(+), 7 deletions(-)

--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -1544,6 +1544,13 @@ static irqreturn_t tc_irq_handler(int ir
 	return IRQ_HANDLED;
 }
 
+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;
@@ -1561,6 +1568,24 @@ static int tc_probe(struct i2c_client *c
 	if (ret && ret != -ENODEV)
 		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))
@@ -1581,13 +1606,6 @@ static int tc_probe(struct i2c_client *c
 		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);