linux-kernel - [PATCH v2 2/2] i2c: imx: defer probing on dma channel request

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Message-Id: <20190116112855.13824-2-laurentiu.tudor@nxp.com>
Date:   Wed, 16 Jan 2019 13:28:55 +0200
From:   Laurentiu Tudor <laurentiu.tudor@....com>
To:     linux-i2c@...r.kernel.org, linux-imx@....com, shawnguo@...nel.org,
        s.hauer@...gutronix.de, kernel@...gutronix.de, wsa@...-dreams.de
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        fabio.estevam@....com, leoyang.li@....com,
        Laurentiu Tudor <laurentiu.tudor@....com>
Subject: [PATCH v2 2/2] i2c: imx: defer probing on dma channel request

If the dma controller is not yet probed, defer i2c probe.
The error path in probe was slightly modified (no functional change)
to avoid triggering this WARN_ON():
"cg-pll0-div1 already disabled
WARNING: CPU: 1 PID: 1 at drivers/clk/clk.c:828 clk_core_disable+0xa8/0xb0"

Signed-off-by: Laurentiu Tudor <laurentiu.tudor@....com>
---
Changes in v2:
 - rebased on latest i2c tree
 - fix small error introduced by a previous commit (first patch)

 drivers/i2c/busses/i2c-imx.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 42fed40198a0..4e34b1572756 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -1111,7 +1111,8 @@ static int i2c_imx_probe(struct platform_device *pdev)
 				pdev->name, i2c_imx);
 	if (ret) {
 		dev_err(&pdev->dev, "can't claim irq %d\n", irq);
-		goto clk_disable;
+		clk_disable_unprepare(i2c_imx->clk);
+		return ret;
 	}
 
 	/* Init queue */
@@ -1161,19 +1162,25 @@ static int i2c_imx_probe(struct platform_device *pdev)
 	pm_runtime_mark_last_busy(&pdev->dev);
 	pm_runtime_put_autosuspend(&pdev->dev);
 
+	/* Init DMA config if supported */
+	ret = i2c_imx_dma_request(i2c_imx, phy_addr);
+	if (ret) {
+		if (ret != -EPROBE_DEFER)
+			dev_info(&pdev->dev, "can't use DMA, using PIO instead.\n");
+		else
+			goto del_adapter;
+	}
+
 	dev_dbg(&i2c_imx->adapter.dev, "claimed irq %d\n", irq);
 	dev_dbg(&i2c_imx->adapter.dev, "device resources: %pR\n", res);
 	dev_dbg(&i2c_imx->adapter.dev, "adapter name: \"%s\"\n",
 		i2c_imx->adapter.name);
 
-	/* Init DMA config if supported */
-	ret = i2c_imx_dma_request(i2c_imx, phy_addr);
-	if (ret < 0)
-		goto clk_notifier_unregister;
-
 	dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");
 	return 0;   /* Return OK */
 
+del_adapter:
+	i2c_del_adapter(&i2c_imx->adapter);
 clk_notifier_unregister:
 	clk_notifier_unregister(i2c_imx->clk, &i2c_imx->clk_change_nb);
 rpm_disable:
@@ -1182,8 +1189,6 @@ static int i2c_imx_probe(struct platform_device *pdev)
 	pm_runtime_set_suspended(&pdev->dev);
 	pm_runtime_dont_use_autosuspend(&pdev->dev);
 
-clk_disable:
-	clk_disable_unprepare(i2c_imx->clk);
 	return ret;
 }
 
-- 
2.17.1