linux-kernel - RE: [PATCH] i2c: imx: support DMA defer probing

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Message-ID:
 <AM0PR0402MB39372D2666789C4A00001303E82F2@AM0PR0402MB3937.eurprd04.prod.outlook.com>
Date: Tue, 26 Nov 2024 06:47:31 +0000
From: Carlos Song <carlos.song@....com>
To: Frank Li <frank.li@....com>
CC: "o.rempel@...gutronix.de" <o.rempel@...gutronix.de>,
	"kernel@...gutronix.de" <kernel@...gutronix.de>, "andi.shyti@...nel.org"
	<andi.shyti@...nel.org>, "shawnguo@...nel.org" <shawnguo@...nel.org>,
	"s.hauer@...gutronix.de" <s.hauer@...gutronix.de>, "festevam@...il.com"
	<festevam@...il.com>, "linux-i2c@...r.kernel.org"
	<linux-i2c@...r.kernel.org>, "imx@...ts.linux.dev" <imx@...ts.linux.dev>,
	"linux-arm-kernel@...ts.infradead.org"
	<linux-arm-kernel@...ts.infradead.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
Subject: RE: [PATCH] i2c: imx: support DMA defer probing



> -----Original Message-----
> From: Frank Li <frank.li@....com>
> Sent: Tuesday, November 26, 2024 1:17 AM
> To: Carlos Song <carlos.song@....com>
> Cc: o.rempel@...gutronix.de; kernel@...gutronix.de; andi.shyti@...nel.org;
> shawnguo@...nel.org; s.hauer@...gutronix.de; festevam@...il.com;
> linux-i2c@...r.kernel.org; imx@...ts.linux.dev;
> linux-arm-kernel@...ts.infradead.org; linux-kernel@...r.kernel.org
> Subject: Re: [PATCH] i2c: imx: support DMA defer probing
> 
> On Mon, Nov 25, 2024 at 09:52:43PM +0800, carlos.song@....com wrote:
> > From: Carlos Song <carlos.song@....com>
> >
> > Return -EPROBE_DEFER when dma_request_slave_channel() because DMA
> > driver have not ready yet.
> 
> wrap at 75 char.
> 

Will fix it at V2.
> >
> > 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@....com>
> > Signed-off-by: Clark Wang <xiaoning.wang@....com>
> > ---
> >  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..ee7070ee9e6e 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 device *dev, dma_addr_t
> > +phy_addr)
> >  {
> 
> Not sure why you change "struct imx_i2c_struct *i2c_imx" to "struct device
> *dev"
> 
Yes, you are right. I really made the redundant fixes. I just need to using this change.
...
/* Functions for DMA support */
-static void i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
+static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
                                                dma_addr_t phy_addr)

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

I will send V2 and fix this.

> > +	struct imx_i2c_struct *i2c_imx = dev_get_drvdata(dev);
> >  	struct imx_i2c_dma *dma;
> >  	struct dma_slave_config dma_sconfig;
> > -	struct device *dev = &i2c_imx->adapter.dev;
> >  	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(&pdev->dev, 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:
> > --
> > 2.34.1
> >