Commit d9a13c08 authored by Carlos Song's avatar Carlos Song Committed by Andi Shyti
Browse files

i2c: imx: support DMA defer probing 



Return -EPROBE_DEFER when dma_request_slave_channel() because DMA driver
have not ready yet.

Move i2c_imx_dma_request() before registering I2C adapter to avoid
infinite loop of .probe() calls to the same driver, see "e8c220fa
Revert "i2c: imx: improve the error handling in i2c_imx_dma_request()""
and "Documentation/driver-api/driver-model/driver.rst".

Use CPU mode to avoid stuck registering i2c adapter when DMA resources
are unavailable.

Signed-off-by: default avatarCarlos Song <carlos.song@nxp.com>
Signed-off-by: default avatarClark Wang <xiaoning.wang@nxp.com>
Acked-by: default avatarAhmad Fatoum <a.fatoum@pengutronix.de>
Acked-by: default avatarOleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20241226062521.1004809-1-carlos.song@nxp.com


Signed-off-by: default avatarAndi Shyti <andi.shyti@kernel.org>
parent 8b56f98b

drivers/i2c/busses/i2c-imx.c

+22 −8
Original line number Diff line number Diff line
@@ -397,17 +397,16 @@ static void i2c_imx_reset_regs(struct imx_i2c_struct *i2c_imx) 
}



/* Functions for DMA support */

static void i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,

						dma_addr_t phy_addr)

static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx, dma_addr_t phy_addr)

{

	struct imx_i2c_dma *dma;

	struct dma_slave_config dma_sconfig;

	struct device *dev = &i2c_imx->adapter.dev;

	struct device *dev = i2c_imx->adapter.dev.parent;

	int ret;



	dma = devm_kzalloc(dev, sizeof(*dma), GFP_KERNEL);

	if (!dma)

		return;

		return -ENOMEM;



	dma->chan_tx = dma_request_chan(dev, "tx");

	if (IS_ERR(dma->chan_tx)) {
@@ -452,7 +451,7 @@ static void i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx, 
	dev_info(dev, "using %s (tx) and %s (rx) for DMA transfers\n",

		dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));



	return;

	return 0;



fail_rx:

	dma_release_channel(dma->chan_rx);
@@ -460,6 +459,8 @@ static void i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx, 
	dma_release_channel(dma->chan_tx);

fail_al:

	devm_kfree(dev, dma);



	return ret;

}



static void i2c_imx_dma_callback(void *arg)
@@ -1802,6 +1803,22 @@ static int i2c_imx_probe(struct platform_device *pdev) 
	if (ret == -EPROBE_DEFER)

		goto clk_notifier_unregister;



	/*

	 * DMA mode should be optional for I2C, when encountering DMA errors,

	 * no need to exit I2C probe. Only print warning to show DMA error and

	 * use PIO mode directly to ensure I2C bus available as much as possible.

	 */

	ret = i2c_imx_dma_request(i2c_imx, phy_addr);

	if (ret) {

		if (ret == -EPROBE_DEFER)

			goto clk_notifier_unregister;

		else if (ret == -ENODEV)

			dev_dbg(&pdev->dev, "Only use PIO mode\n");

		else

			dev_warn(&pdev->dev, "Failed to setup DMA (%pe), only use PIO mode\n",

				 ERR_PTR(ret));

	}



	/* Add I2C adapter */

	ret = i2c_add_numbered_adapter(&i2c_imx->adapter);

	if (ret < 0)
@@ -1816,9 +1833,6 @@ static int i2c_imx_probe(struct platform_device *pdev) 
		i2c_imx->adapter.name);

	dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");



	/* Init DMA config if supported */

	i2c_imx_dma_request(i2c_imx, phy_addr);



	return 0;   /* Return OK */



clk_notifier_unregister: