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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Lucas Stach <l.stach@pengutronix.de>,
        Marek Vasut <marex@denx.de>, Jonas Karlman <jonas@kwiboo.se>,
        Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
        Maxime Ripard <maxime@cerno.tech>,
        Neil Armstrong <narmstrong@baylibre.com>,
        Robert Foss <robert.foss@linaro.org>,
        Sam Ravnborg <sam@ravnborg.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.18 0305/1095] drm/bridge: tc358767: Make sure Refclk clock are enabled
Date:   Mon, 15 Aug 2022 19:55:04 +0200
Message-Id: <20220815180442.405202606@linuxfoundation.org>
In-Reply-To: <20220815180429.240518113@linuxfoundation.org>
References: <20220815180429.240518113@linuxfoundation.org>
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From: Marek Vasut <marex@denx.de>

[ 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 835a146a0196..5a51c1699b29 100644
--- a/drivers/gpu/drm/bridge/tc358767.c
+++ b/drivers/gpu/drm/bridge/tc358767.c
@@ -1576,6 +1576,13 @@ 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;
@@ -1592,6 +1599,24 @@ 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))
@@ -1612,13 +1637,6 @@ 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);
-- 
2.35.1