linux-kernel - Re: [PATCHv2] i2c: adds support for i2c bus on Frescale CPM1/CPM2 controllers

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Date:	Wed, 23 Jan 2008 11:29:41 +0100
From:	Jean Delvare <khali@...ux-fr.org>
To:	Jochen Friedrich <jochen@...am.de>
Cc:	Stephen Rothwell <sfr@...b.auug.org.au>,
	Jon Smirl <jonsmirl@...il.com>, linuxppc-dev@...abs.org,
	linux-kernel@...r.kernel.org, Scott Wood <scottwood@...escale.com>
Subject: Re: [PATCHv2] i2c: adds support for i2c bus on Frescale CPM1/CPM2 
 controllers

Hi Jochen,

Sorry for the late answer.

On Thu, 3 Jan 2008 10:41:21 +1100, Stephen Rothwell wrote:
> Hi Jochen,
> 
> Just a few trivial things.
> 
> On Wed, 02 Jan 2008 20:52:00 +0100 Jochen Friedrich <jochen@...am.de> wrote:
> >
> > +++ b/drivers/i2c/busses/i2c-cpm.c
> > +
> > +static irqreturn_t cpm_i2c_interrupt(int irq, void *dev_id)
> > +{
> > +	struct i2c_adapter *adap;
> > +	struct cpm_i2c *cpm;
> > +	struct i2c_reg __iomem *i2c_reg;
> > +	int i;
> > +
> > +	adap = (struct i2c_adapter *) dev_id;
> 
> This cast is unnecessary. In fact, you could just pass dev_id to the
> following call to i2c_get_adapdata() and eliminate adap completely.
> 
> > +	/* Get 'me going again.
> > +	 */
> 
> For short comments, just make them one line.  Similarly later as well.
> 
> > +	/* This chip can't do zero length writes. However, the i2c core uses
> > +	   them to scan for devices. The best we can do is to convert them
> > +	   into 1 byte reads */
> 
> For multiline comments, we normally do
> /*
>  * blah ...
>  * more blah
>  */
> 
> > +static int cpm_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
> > +{
> > +
> > +	while (tptr < num) {
> > +		/* Check for outstanding messages */
> > +		dev_dbg(&adap->dev, "test ready.\n");
> > +		if (!(tbdf[tptr].cbd_sc & BD_SC_READY)) {
> > +			dev_dbg(&adap->dev, "ready.\n");
> > +			rmsg = &msgs[tptr];
> > +			ret = cpm_i2c_check_message(adap, rmsg, tptr, rptr);
> > +			tptr++;
> > +			if (rmsg->flags & I2C_M_RD)
> > +				rptr++;
> > +			if (ret) {
> > +				cpm_i2c_force_close(adap);
> > +				mutex_unlock(&cpm->i2c_mutex);
> > +				return ret;
> > +			}
> > +		} else {
> > +			dev_dbg(&adap->dev, "not ready.\n");
> > +			ret = wait_event_interruptible_timeout(cpm->i2c_wait,
> > +				!(tbdf[tptr].cbd_sc & BD_SC_READY), 1 * HZ);
> > +			if (ret == 0) {
> > +				cpm_i2c_force_close(adap);
> > +				dev_dbg(&adap->dev, "I2C read: timeout!\n");
> > +				mutex_unlock(&cpm->i2c_mutex);
> > +				return -EREMOTEIO;
> > +			}
> 
> You might want to consolidate the two error paths above using gotos to an
> error return section below.
> 
> > +static void of_register_i2c_devices(struct i2c_adapter *adap,
> > +				    struct device_node *adap_node)
> > +{
> > +	struct device_node *node = NULL;
> > +
> > +	while ((node = of_get_next_child(adap_node, node))) {
> 
> Use
> 	for_each_child_of_node(adap_node, node) {
> instead and you don't need to initialise "node" above.
> 
> > +static struct of_device_id cpm_i2c_match[] = {
> 
> const?

Do you have an updated patch addressing Stephen's comment?

Note: you'd rather send updates of this patch to the i2c list rather
than LKML.

Thanks,
-- 
Jean Delvare
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