linux-kernel - RE: [PATCH] i2c: imx: fix divide by zero warning

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Message-ID:
 <AM0PR0402MB39372A814D43DBCD5AAD1595E82F2@AM0PR0402MB3937.eurprd04.prod.outlook.com>
Date: Tue, 26 Nov 2024 02:04:02 +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: fix divide by zero warning



> -----Original Message-----
> From: Frank Li <frank.li@....com>
> Sent: Tuesday, November 26, 2024 1:18 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: fix divide by zero warning
> 
> On Mon, Nov 25, 2024 at 10:15:21PM +0800, carlos.song@....com wrote:
> > From: Carlos Song <carlos.song@....com>
> >
> > Add "i2c_clk_rate / 2" check to avoid "divide by zero warning".
> > i2c_clk_rate may be zero if i2c clock is disabled.
> >
> > Signed-off-by: Carlos Song <carlos.song@....com>
> > Signed-off-by: Clark Wang <xiaoning.wang@....com>
> > Signed-off-by: Haibo Chen <haibo.chen@....com>
> > ---
> 
> You sent this patch twice?
> 
Yes, because I meet a net error, I send the patch out and wait for a half of hour, but I don't see the mail in the mail list, so I send it again, but another one come in
after 1 hour.. You can dismiss the same one.

> Reviewed-by: Frank Li <Frank.Li@....com>
> 
> >  drivers/i2c/busses/i2c-imx.c | 23 +++++++++++++++++------
> >  1 file changed, 17 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/i2c/busses/i2c-imx.c
> > b/drivers/i2c/busses/i2c-imx.c index 2c782cdc26bd..5ed4cb61e262 100644
> > --- a/drivers/i2c/busses/i2c-imx.c
> > +++ b/drivers/i2c/busses/i2c-imx.c
> > @@ -623,8 +623,8 @@ static int i2c_imx_acked(struct imx_i2c_struct
> *i2c_imx)
> >  	return 0;
> >  }
> >
> > -static void i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
> > -			    unsigned int i2c_clk_rate)
> > +static int i2c_imx_set_clk(struct imx_i2c_struct *i2c_imx,
> > +			   unsigned int i2c_clk_rate)
> >  {
> >  	struct imx_i2c_clk_pair *i2c_clk_div = i2c_imx->hwdata->clk_div;
> >  	unsigned int div;
> > @@ -639,7 +639,11 @@ static void i2c_imx_set_clk(struct imx_i2c_struct
> > *i2c_imx,
> >
> >  	/* Divider value calculation */
> >  	if (i2c_imx->cur_clk == i2c_clk_rate)
> > -		return;
> > +		return 0;
> > +
> > +	/* Keep the denominator of the following program always NOT equal to 0.
> */
> > +	if (!(i2c_clk_rate / 2))
> > +		return -EINVAL;
> >
> >  	i2c_imx->cur_clk = i2c_clk_rate;
> >
> > @@ -670,6 +674,8 @@ static void i2c_imx_set_clk(struct imx_i2c_struct
> *i2c_imx,
> >  	dev_dbg(&i2c_imx->adapter.dev, "IFDR[IC]=0x%x, REAL DIV=%d\n",
> >  		i2c_clk_div[i].val, i2c_clk_div[i].div);  #endif
> > +
> > +	return 0;
> >  }
> >
> >  static int i2c_imx_clk_notifier_call(struct notifier_block *nb, @@
> > -679,11 +685,12 @@ static int i2c_imx_clk_notifier_call(struct notifier_block
> *nb,
> >  	struct imx_i2c_struct *i2c_imx = container_of(nb,
> >  						      struct imx_i2c_struct,
> >  						      clk_change_nb);
> > +	int ret = 0;
> >
> >  	if (action & POST_RATE_CHANGE)
> > -		i2c_imx_set_clk(i2c_imx, ndata->new_rate);
> > +		ret = i2c_imx_set_clk(i2c_imx, ndata->new_rate);
> >
> > -	return NOTIFY_OK;
> > +	return notifier_from_errno(ret);
> >  }
> >
> >  static int i2c_imx_start(struct imx_i2c_struct *i2c_imx, bool atomic)
> > @@ -1782,7 +1789,11 @@ static int i2c_imx_probe(struct platform_device
> *pdev)
> >  		i2c_imx->bitrate = pdata->bitrate;
> >  	i2c_imx->clk_change_nb.notifier_call = i2c_imx_clk_notifier_call;
> >  	clk_notifier_register(i2c_imx->clk, &i2c_imx->clk_change_nb);
> > -	i2c_imx_set_clk(i2c_imx, clk_get_rate(i2c_imx->clk));
> > +	ret = i2c_imx_set_clk(i2c_imx, clk_get_rate(i2c_imx->clk));
> > +	if (ret < 0) {
> > +		dev_err(&pdev->dev, "can't get I2C clock\n");
> > +		goto clk_notifier_unregister;
> > +	}
> >
> >  	i2c_imx_reset_regs(i2c_imx);
> >
> > --
> > 2.34.1
> >