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

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Message-Id: <20080103104121.58697148.sfr@canb.auug.org.au>
Date:	Thu, 3 Jan 2008 10:41:21 +1100
From:	Stephen Rothwell <sfr@...b.auug.org.au>
To:	Jochen Friedrich <jochen@...am.de>
Cc:	Jon Smirl <jonsmirl@...il.com>, Jean Delvare <khali@...ux-fr.org>,
	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,

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?

-- 
Cheers,
Stephen Rothwell                    sfr@...b.auug.org.au
http://www.canb.auug.org.au/~sfr/

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