diff mbox series

[v2] i2c: imx: support DMA defer probing

Message ID 20241126082535.1878554-1-carlos.song@nxp.com (mailing list archive)
State New
Headers show
Series [v2] i2c: imx: support DMA defer probing | expand

Commit Message

Carlos Song Nov. 26, 2024, 8:25 a.m. UTC
From: Carlos Song <carlos.song@nxp.com>

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>
---
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 | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

Comments

Marc Kleine-Budde Nov. 26, 2024, 8:55 a.m. UTC | #1
On 26.11.2024 16:25:35, carlos.song@nxp.com wrote:
> From: Carlos Song <carlos.song@nxp.com>
> 
> 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>
> ---
> 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 | 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 5ed4cb61e262..4e5633166a1e 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 +1804,13 @@ static int i2c_imx_probe(struct platform_device *pdev)
>  	if (ret == -EPROBE_DEFER)
>  		goto clk_notifier_unregister;
>  
> +	/* Init DMA config if supported */
> +	ret = i2c_imx_dma_request(i2c_imx, phy_addr);
> +	if (ret == -EPROBE_DEFER) {
> +		dev_err(&pdev->dev, "DMA not ready, go defer probe!\n");
> +		goto clk_notifier_unregister;
> +	}

Don't spam the logs if the driver defers probing, it's not a error. And
it looks strange to ignore all other errors here. Either add a comment
here, something like "continue without DMA", or let the function return
0 in case the driver should continue and propagate the error if the
caller should take care of it.

Marc
Ahmad Fatoum Nov. 26, 2024, 9:56 a.m. UTC | #2
Hello Carlos,

On 26.11.24 09:25, carlos.song@nxp.com wrote:
> From: Carlos Song <carlos.song@nxp.com>
> 
> 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.

Wouldn't this break probe for all i2c-imx users who have CONFIG_IMX_SDMA
disabled?

Also I am wondering on what kernel version and what configuration
(CONFIG_I2C_IMX=?, CONFIG_IMX_SDMA=?) you have that made you run into
this situation.

I'd have expected that with fw_devlink enabled, the I2C controller wouldn't
be probed before the DMA provider is available.

Cheers,
Ahmad

> 
> Signed-off-by: Carlos Song <carlos.song@nxp.com>
> Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
> ---
> 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 | 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 5ed4cb61e262..4e5633166a1e 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 +1804,13 @@ static int i2c_imx_probe(struct platform_device *pdev)
>  	if (ret == -EPROBE_DEFER)
>  		goto clk_notifier_unregister;
>  
> +	/* Init DMA config if supported */
> +	ret = i2c_imx_dma_request(i2c_imx, phy_addr);
> +	if (ret == -EPROBE_DEFER) {
> +		dev_err(&pdev->dev, "DMA not ready, go defer probe!\n");
> +		goto clk_notifier_unregister;
> +	}
> +
>  	/* Add I2C adapter */
>  	ret = i2c_add_numbered_adapter(&i2c_imx->adapter);
>  	if (ret < 0)
> @@ -1817,9 +1825,6 @@ 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:
Carlos Song Nov. 26, 2024, 10:15 a.m. UTC | #3
> -----Original Message-----
> From: Marc Kleine-Budde <mkl@pengutronix.de>
> Sent: Tuesday, November 26, 2024 4:56 PM
> To: Carlos Song <carlos.song@nxp.com>
> Cc: Frank Li <frank.li@nxp.com>; o.rempel@pengutronix.de;
> kernel@pengutronix.de; andi.shyti@kernel.org; shawnguo@kernel.org;
> s.hauer@pengutronix.de; festevam@gmail.com; imx@lists.linux.dev;
> linux-i2c@vger.kernel.org; linux-arm-kernel@lists.infradead.org;
> linux-kernel@vger.kernel.org
> Subject: [EXT] Re: [PATCH v2] i2c: imx: support DMA defer probing
> 
> On 26.11.2024 16:25:35, carlos.song@nxp.com wrote:
> > From: Carlos Song <carlos.song@nxp.com>
> >
> > 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>
> > ---
> > 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 | 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 5ed4cb61e262..4e5633166a1e 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 +1804,13 @@
> > static int i2c_imx_probe(struct platform_device *pdev)
> >  	if (ret == -EPROBE_DEFER)
> >  		goto clk_notifier_unregister;
> >
> > +	/* Init DMA config if supported */
> > +	ret = i2c_imx_dma_request(i2c_imx, phy_addr);
> > +	if (ret == -EPROBE_DEFER) {
> > +		dev_err(&pdev->dev, "DMA not ready, go defer probe!\n");
> > +		goto clk_notifier_unregister;
> > +	}
> 
> Don't spam the logs if the driver defers probing, it's not a error. And it looks
> strange to ignore all other errors here. Either add a comment here, something
> like "continue without DMA", or let the function return
> 0 in case the driver should continue and propagate the error if the caller should
> take care of it.
> 

Hi,
Thank you for your suggestion! I agree with you.
I will change to this logic:
	ret = i2c_imx_dma_request(i2c_imx, phy_addr);
	if (ret) {
		if (ret == -EPROBE_DEFER)
			goto clk_notifier_unregister;
		dev_info(&pdev->dev, "use pio mode\n");
	}

Ret = 0  ----->  enable DMA successfully  -------> no print
Ret!=0  ----->  defer probe ---------> no print and try again
Ret!=0  ----->  fail to enable DMA ------> remind now is using pio mode

Do you think the logic is acceptable?

> Marc
> 
> --
> Pengutronix e.K.                 | Marc Kleine-Budde          |
> Embedded Linux                   | https://www.pengutronix.de |
> Vertretung Nürnberg              | Phone: +49-5121-206917-129 |
> Amtsgericht Hildesheim, HRA 2686 | Fax:   +49-5121-206917-9   |
Marc Kleine-Budde Nov. 26, 2024, 10:23 a.m. UTC | #4
On 26.11.2024 10:15:27, Carlos Song wrote:
> > >  static void i2c_imx_dma_callback(void *arg) @@ -1803,6 +1804,13 @@
> > > static int i2c_imx_probe(struct platform_device *pdev)
> > >  	if (ret == -EPROBE_DEFER)
> > >  		goto clk_notifier_unregister;
> > >
> > > +	/* Init DMA config if supported */
> > > +	ret = i2c_imx_dma_request(i2c_imx, phy_addr);
> > > +	if (ret == -EPROBE_DEFER) {
> > > +		dev_err(&pdev->dev, "DMA not ready, go defer probe!\n");
> > > +		goto clk_notifier_unregister;
> > > +	}
> > 
> > Don't spam the logs if the driver defers probing, it's not a error. And it looks
> > strange to ignore all other errors here. Either add a comment here, something
> > like "continue without DMA", or let the function return
> > 0 in case the driver should continue and propagate the error if the caller should
> > take care of it.
> > 
> 
> Hi,
> Thank you for your suggestion! I agree with you.
> I will change to this logic:
> 	ret = i2c_imx_dma_request(i2c_imx, phy_addr);
> 	if (ret) {
> 		if (ret == -EPROBE_DEFER)
> 			goto clk_notifier_unregister;
> 		dev_info(&pdev->dev, "use pio mode\n");
> 	}
> 
> Ret = 0  ----->  enable DMA successfully  -------> no print
> Ret!=0  ----->  defer probe ---------> no print and try again
> Ret!=0  ----->  fail to enable DMA ------> remind now is using pio mode
> 
> Do you think the logic is acceptable?

Yes, the other option is to move the logic into i2c_imx_dma_request()
and let it return 0 in case of DMA or fallback to PIO, or an error in
case of probe defer or a fatal error.

This way the probe function will look like this:

     ret = i2c_imx_dma_request(i2c_imx, phy_addr);
     if (ret)
                return dev_err_probe(&pdev->dev, ret, "Failed to setup DMA\n");


regards,
Marc
diff mbox series

Patch

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 5ed4cb61e262..4e5633166a1e 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 +1804,13 @@  static int i2c_imx_probe(struct platform_device *pdev)
 	if (ret == -EPROBE_DEFER)
 		goto clk_notifier_unregister;
 
+	/* Init DMA config if supported */
+	ret = i2c_imx_dma_request(i2c_imx, phy_addr);
+	if (ret == -EPROBE_DEFER) {
+		dev_err(&pdev->dev, "DMA not ready, go defer probe!\n");
+		goto clk_notifier_unregister;
+	}
+
 	/* Add I2C adapter */
 	ret = i2c_add_numbered_adapter(&i2c_imx->adapter);
 	if (ret < 0)
@@ -1817,9 +1825,6 @@  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: