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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, Jerome Brunet <jbrunet@baylibre.com>,
        Wolfram Sang <wsa@kernel.org>
Subject: [PATCH 5.8 038/124] i2c: meson: keep peripheral clock enabled
Date:   Mon, 12 Oct 2020 15:30:42 +0200
Message-Id: <20201012133148.691247743@linuxfoundation.org>
In-Reply-To: <20201012133146.834528783@linuxfoundation.org>
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From: Jerome Brunet <jbrunet@baylibre.com>

commit 79e137b1540165f788394658442284d55a858984 upstream.

SCL rate appears to be different than what is expected. For example,
We get 164kHz on i2c3 of the vim3 when 400kHz is expected. This is
partially due to the peripheral clock being disabled when the clock is
set.

Let's keep the peripheral clock on after probe to fix the problem. This
does not affect the SCL output which is still gated when i2c is idle.

Fixes: 09af1c2fa490 ("i2c: meson: set clock divider in probe instead of setting it for each transfer")
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/i2c/busses/i2c-meson.c |   10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

--- a/drivers/i2c/busses/i2c-meson.c
+++ b/drivers/i2c/busses/i2c-meson.c
@@ -370,16 +370,12 @@ static int meson_i2c_xfer_messages(struc
 	struct meson_i2c *i2c = adap->algo_data;
 	int i, ret = 0;
 
-	clk_enable(i2c->clk);
-
 	for (i = 0; i < num; i++) {
 		ret = meson_i2c_xfer_msg(i2c, msgs + i, i == num - 1, atomic);
 		if (ret)
 			break;
 	}
 
-	clk_disable(i2c->clk);
-
 	return ret ?: i;
 }
 
@@ -448,7 +444,7 @@ static int meson_i2c_probe(struct platfo
 		return ret;
 	}
 
-	ret = clk_prepare(i2c->clk);
+	ret = clk_prepare_enable(i2c->clk);
 	if (ret < 0) {
 		dev_err(&pdev->dev, "can't prepare clock\n");
 		return ret;
@@ -470,7 +466,7 @@ static int meson_i2c_probe(struct platfo
 
 	ret = i2c_add_adapter(&i2c->adap);
 	if (ret < 0) {
-		clk_unprepare(i2c->clk);
+		clk_disable_unprepare(i2c->clk);
 		return ret;
 	}
 
@@ -488,7 +484,7 @@ static int meson_i2c_remove(struct platf
 	struct meson_i2c *i2c = platform_get_drvdata(pdev);
 
 	i2c_del_adapter(&i2c->adap);
-	clk_unprepare(i2c->clk);
+	clk_disable_unprepare(i2c->clk);
 
 	return 0;
 }