linux-kernel - [PATCH] i2c: layerscape: use PIO when fail to request dma channel

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Date:   Fri, 24 May 2019 03:03:36 +0000
From:   Qiang Zhao <qiang.zhao@....com>
To:     "shawnguo@...nel.org" <shawnguo@...nel.org>
CC:     "linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Qiang Zhao <qiang.zhao@....com>
Subject: [PATCH] i2c: layerscape: use PIO when fail to request dma channel

When fail to request DMA TX/RX channel, use PIO instead for layerscape.

Signed-off-by: Zhao Qiang <qiang.zhao@....com>
---
 drivers/i2c/busses/i2c-imx.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 98b278613cf2..39a5ab4cf332 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -347,9 +347,13 @@ static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
 
 	dma->chan_tx = dma_request_chan(dev, "tx");
 	if (IS_ERR(dma->chan_tx)) {
+#ifdef CONFIG_ARCH_LAYERSCAPE
+		dev_dbg(dev, "can't request DMA tx channel\n");
+#else
 		ret = PTR_ERR(dma->chan_tx);
 		if (ret != -ENODEV && ret != -EPROBE_DEFER)
 			dev_err(dev, "can't request DMA tx channel (%d)\n", ret);
+#endif
 		goto fail_al;
 	}
 
@@ -366,9 +370,13 @@ static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
 
 	dma->chan_rx = dma_request_chan(dev, "rx");
 	if (IS_ERR(dma->chan_rx)) {
+#ifdef CONFIG_ARCH_LAYERSCAPE
+		dev_dbg(dev, "can't request DMA rx channel\n");
+#else
 		ret = PTR_ERR(dma->chan_rx);
 		if (ret != -ENODEV && ret != -EPROBE_DEFER)
 			dev_err(dev, "can't request DMA rx channel (%d)\n", ret);
+#endif
 		goto fail_tx;
 	}
 
@@ -396,6 +404,9 @@ static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
 	dma_release_channel(dma->chan_tx);
 fail_al:
 	devm_kfree(dev, dma);
+#ifdef CONFIG_ARCH_LAYERSCAPE
+	dev_info(dev, "can't use DMA, using PIO instead.\n");
+#endif
 	/* return successfully if there is no dma support */
 	return ret == -ENODEV ? 0 : ret;
 }
-- 
2.17.1