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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, Chen-Yu Tsai <wens@csie.org>,
        Maxime Ripard <maxime.ripard@free-electrons.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.9 016/241] drm/sun4i: Fix TCON clock and regmap initialization sequence
Date:   Mon, 19 Mar 2018 19:04:41 +0100
Message-Id: <20180319180751.842712764@linuxfoundation.org>
In-Reply-To: <20180319180751.172155436@linuxfoundation.org>
References: <20180319180751.172155436@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Chen-Yu Tsai <wens@csie.org>


[ Upstream commit 4c7f16d14a33a9cfb4af9cb780d8a73bcca64a92 ]

The TCON driver calls sun4i_tcon_init_regmap and sun4i_tcon_init_clocks
in its bind function. The former creates a regmap and writes to several
register to clear its configuration to a known default. The latter
initializes various clocks. This includes enabling the bus clock for
register access and creating the dotclock.

In order for the first step's writes to work, the bus clock must be
enabled which is done in the second step. but the dotclock's ops use
the regmap created in the first step.

Rearrange the function calls such that the clocks are initialized before
the regmap, and split out the dot clock creation to after the regmap is
initialized.

Fixes: 9026e0d122ac ("drm: Add Allwinner A10 Display Engine support")
Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/gpu/drm/sun4i/sun4i_tcon.c |   22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -336,12 +336,11 @@ static int sun4i_tcon_init_clocks(struct
 		}
 	}
 
-	return sun4i_dclk_create(dev, tcon);
+	return 0;
 }
 
 static void sun4i_tcon_free_clocks(struct sun4i_tcon *tcon)
 {
-	sun4i_dclk_free(tcon);
 	clk_disable_unprepare(tcon->clk);
 }
 
@@ -506,22 +505,28 @@ static int sun4i_tcon_bind(struct device
 		return ret;
 	}
 
+	ret = sun4i_tcon_init_clocks(dev, tcon);
+	if (ret) {
+		dev_err(dev, "Couldn't init our TCON clocks\n");
+		goto err_assert_reset;
+	}
+
 	ret = sun4i_tcon_init_regmap(dev, tcon);
 	if (ret) {
 		dev_err(dev, "Couldn't init our TCON regmap\n");
-		goto err_assert_reset;
+		goto err_free_clocks;
 	}
 
-	ret = sun4i_tcon_init_clocks(dev, tcon);
+	ret = sun4i_dclk_create(dev, tcon);
 	if (ret) {
-		dev_err(dev, "Couldn't init our TCON clocks\n");
-		goto err_assert_reset;
+		dev_err(dev, "Couldn't create our TCON dot clock\n");
+		goto err_free_clocks;
 	}
 
 	ret = sun4i_tcon_init_irq(dev, tcon);
 	if (ret) {
 		dev_err(dev, "Couldn't init our TCON interrupts\n");
-		goto err_free_clocks;
+		goto err_free_dotclock;
 	}
 
 	ret = sun4i_rgb_init(drm);
@@ -530,6 +535,8 @@ static int sun4i_tcon_bind(struct device
 
 	return 0;
 
+err_free_dotclock:
+	sun4i_dclk_free(tcon);
 err_free_clocks:
 	sun4i_tcon_free_clocks(tcon);
 err_assert_reset:
@@ -542,6 +549,7 @@ static void sun4i_tcon_unbind(struct dev
 {
 	struct sun4i_tcon *tcon = dev_get_drvdata(dev);
 
+	sun4i_dclk_free(tcon);
 	sun4i_tcon_free_clocks(tcon);
 }