On 27.11.2024 15:44:58, carlos.song@xxxxxxx wrote:
> From: Carlos Song <carlos.song@xxxxxxx>
>
> 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@xxxxxxx>
> Signed-off-by: Clark Wang <xiaoning.wang@xxxxxxx>
> ---
> Change for V3:
> - According to Marc's comment, remove error print when defer probe.
> Add info log when DMA has not been enabled and add error log when
> DMA error, both won't stuck the i2c adapter register, just for reminding,
> i2c adapter is working only in PIO mode.
> Change for V2:
> - According to Frank's comments, wrap at 75 char and Simplify fix code
> at i2c_imx_dma_request().
> - Use strict patch check, fix alignment warning at i2c_imx_dma_request()
> ---
> drivers/i2c/busses/i2c-imx.c | 31 +++++++++++++++++++++++--------
> 1 file changed, 23 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 5ed4cb61e262..47112a38d034 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -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)
> @@ -1803,6 +1804,23 @@ static int i2c_imx_probe(struct platform_device *pdev)
> if (ret == -EPROBE_DEFER)
> goto clk_notifier_unregister;
>
> + /*
> + * Init DMA config if supported, -ENODEV means DMA not enabled at
> + * this platform, that is not a real error, so just remind "only
> + * PIO mode is used". If DMA is enabled, but meet error when request
> + * DMA channel, error should be showed in probe error log. PIO mode
> + * should be available regardless of DMA.
> + */
> + ret = i2c_imx_dma_request(i2c_imx, phy_addr);
> + if (ret) {
> + if (ret == -EPROBE_DEFER)
> + goto clk_notifier_unregister;
> + else if (ret == -ENODEV)
> + dev_info(&pdev->dev, "Only use PIO mode\n");
On a system without DMA configured, with this patch we now get this info
message that wasn't there before. I think this might annoy some people,
so you should remove it.
regards,
Marc
> + else
> + dev_err_probe(&pdev->dev, ret, "Failed to setup DMA, only use PIO mode\n");
> + }
> +
> /* Add I2C adapter */
> ret = i2c_add_numbered_adapter(&i2c_imx->adapter);
> if (ret < 0)
> @@ -1817,9 +1835,6 @@ 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:
> --
> 2.34.1
>
>
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
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Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-9 |
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