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i2c: imx: support DMA defer probing

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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 "e8c220fac415
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: Carlos Song <carlos.song@nxp.com>
Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
Acked-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Link: https://lore.kernel.org/r/20241226062521.1004809-1-carlos.song@nxp.com
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
This commit is contained in:
Carlos Song 2024-12-26 14:25:21 +08:00 committed by Andi Shyti
parent 8b56f98b28
commit d9a13c08f8
1 changed files with 22 additions and 8 deletions
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30
drivers/i2c/busses/i2c-imx.c
View File

@ -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: