Re: [MeeGo-Dev][PATCH] Topcliff: Update PCH_I2C driver to 2.6.35

From: Joe Perches <joe@perches.com>
To: Masayuki Ohtak <masa-korg@dsn.okisemi.com>
Cc: "Jean Delvare (PC drivers, core)" <khali@linux-fr.org>,
	"Ben Dooks (embedded platforms)" <ben-linux@fluff.org>,
	Crane Cai <crane.cai@amd.com>,
	Samuel Ortiz <sameo@linux.intel.com>,
	Linus Walleij <linus.walleij@stericsson.com>,
	Ralf Baechle <ralf@linux-mips.org>,
	srinidhi kasagar <srinidhi.kasagar@stericsson.com>,
	linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
	yong.y.wang@intel.com, qi.wang@intel.com,
	andrew.chih.howe.khor@intel.com, arjan@linux.intel.com,
	Tomoya MORINAGA <morinaga526@dsn.okisemi.com>,
	Arnd Bergmann <arnd@arndb.de>
Subject: Re: [MeeGo-Dev][PATCH] Topcliff: Update PCH_I2C driver to 2.6.35
Date: Fri, 03 Sep 2010 01:10:37 -0700	[thread overview]
Message-ID: <1283501437.1797.441.camel@Joe-Laptop> (raw)
In-Reply-To: <4C80A089.508@dsn.okisemi.com>

On Fri, 2010-09-03 at 16:15 +0900, Masayuki Ohtak wrote:
[]
> +#define pch_dbg(adap, fmt, arg...)  \
> +	dev_dbg(adap->pch_adapter.dev.parent, "%s :"fmt, __func__, ##arg)
> +
> +#define pch_err(adap, fmt, arg...)  \
> +	dev_err(adap->pch_adapter.dev.parent, "%s :"fmt, __func__, ##arg)
> +
> +#define pch_pci_err(pdev, fmt, arg...)  \
> +				dev_err(&pdev->dev, "%s :"fmt, __func__, ##arg)
> +#define pch_pci_dbg(pdev, fmt, arg...)  \
> +				dev_dbg(&pdev->dev, "%s :"fmt, __func__, ##arg)

OK, but it seems careless because the two types
are not uniformly indented, there's a blank line
between pch_dbg and pch_err, and the two pch_pci_<level>
defines are in the reverse order without a blank line
between them. 

I think it's better to use separate multiple strings
that are concatentated by the preprocessor like:
	"%s :" fmt
not
	"%s :"fmt

Almost all code in kernel uses "%s: " to format __func__.
Some use "%s(): ".  I think "%s :" is unique.

The rest of the logging messages look good.

Some other comments:

> +	if ((pch_wait_for_xfer_complete(adap) == 0) &&
> +						(pch_getack(adap) == 0)) {

This would look better as:

	if ((pch_wait_for_xfer_complete(adap) == 0) &&
	    (pch_getack(adap) == 0)) {

> +	if ((pch_wait_for_xfer_complete(adap) == 0)
> +					    && (pch_getack(adap) == 0)) {

Here too.

> +	for (i = 0; i < PCH_MAX_CHN; i++) {
> +		while ((adap_info->pch_data[i].pch_xfer_in_progress)) {
> +			/* Wait until all channel transfers are completed */
> +			msleep(1);
> +		}
> +		/* Disable the i2c interrupts */
> +		pch_disbl_int(&adap_info->pch_data[i]);
> +	}

Would it be better to disable all possible interrupts first
or do you need to disable them in order?

Something like:

	bool *disabled = kzalloc(PCH_MAX_CHN * sizeof(bool), GFP_KERNEL);
/*
 * or a static with a memset, or check something
 * like pch_is_int_enabled(&adap_info->pch_data[i])
 * then remove the else because the kzalloc couldn't fail.
 */
	if (disabled) {
		bool alldone;
		do {
			alldone = true;
			for (i = 0; i < PCH_MAX_CHN; i++) {
				if (!adap_info->pch_data[i].pch_xfer_in_progress &&
				    !disabled[i])) {
					pch_disbl_int(&adap_info->pch_data[i]);
					disabled[i] = true;
				} else
					alldone = false;
			}
			if (!alldone) {
				/* Wait until all channel transfers are completed */
				msleep(1);
			}
		} while (!alldone);
		kfree(disabled);

/* remove the else if there's a static etc */

	} else {
		for (i = 0; i < PCH_MAX_CHN; i++) {
			while ((adap_info->pch_data[i].pch_xfer_in_progress)) {
				/* Wait until all channel transfers are completed */
				msleep(1);
			}
			/* Disable the i2c interrupts */
			pch_disbl_int(&adap_info->pch_data[i]);
		}
	}

cheers, Joe