linux-kernel - Re: [PATCH 4/5] netdev/phy: Add driver for Broadcom BCM87XX 10G Ethernet PHYs

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Message-ID: <1337711674.8664.5.camel@joe2Laptop>
Date:	Tue, 22 May 2012 11:34:34 -0700
From:	Joe Perches <joe@...ches.com>
To:	David Daney <david.daney@...ium.com>
Cc:	David Daney <ddaney.cavm@...il.com>,
	"devicetree-discuss@...ts.ozlabs.org" 
	<devicetree-discuss@...ts.ozlabs.org>,
	Grant Likely <grant.likely@...retlab.ca>,
	Rob Herring <rob.herring@...xeda.com>,
	"David S. Miller" <davem@...emloft.net>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-mips@...ux-mips.org" <linux-mips@...ux-mips.org>,
	Fleming Andy-AFLEMING <afleming@...escale.com>
Subject: Re: [PATCH 4/5] netdev/phy: Add driver for Broadcom BCM87XX 10G
 Ethernet PHYs

On Tue, 2012-05-22 at 11:26 -0700, David Daney wrote:
> On 05/22/2012 11:17 AM, Joe Perches wrote:
> > On Tue, 2012-05-22 at 10:59 -0700, David Daney wrote:
> >> From: David Daney<david.daney@...ium.com>
> >
> > trivia:
> 
> As long as we are splitting hairs...

and zooming in and enhancing...

> >
> >> diff --git a/drivers/net/phy/bcm87xx.c b/drivers/net/phy/bcm87xx.c
> > []
> >> @@ -0,0 +1,237 @@
> >
> >> +static int bcm87xx_of_reg_init(struct phy_device *phydev)
> >> +{
> >> +	const __be32 *paddr;
> >> +	int len, i, ret;
> >> +
> >> +	if (!phydev->dev.of_node)
> >> +		return 0;
> >> +
> >> +	paddr = of_get_property(phydev->dev.of_node,
> >> +				"broadcom,c45-reg-init",&len);
> >> +	if (!paddr || len<  (4 * sizeof(*paddr)))
> >> +		return 0;
> >> +
> >> +	ret = 0;
> >> +	len /= sizeof(*paddr);
> >> +	for (i = 0; i<  len - 3; i += 4) {
> >> +		u16 devid = be32_to_cpup(paddr + i);
> >> +		u16 reg = be32_to_cpup(paddr + i + 1);
> >> +		u16 mask = be32_to_cpup(paddr + i + 2);
> >> +		u16 val_bits = be32_to_cpup(paddr + i + 3);
> >> +		int val;
> >
> > These might read better as
> >
> > 	len /= 4;
> 
> Where did the magic value of 4 come from?

equivalence to the original for loop

	for (i = 0; i < len - 3; i += 4) {

> > 	for (i = 0; i<  len; i++) {

> > 		u16 devid	= be32_to_cpu(*paddr++);
> > 		u16 reg		= be32_to_cpu(*paddr++);
> > 		u16 mask	= be32_to_cpu(*paddr++);
> > 		u16 val_bits	= be32_to_cpu(*paddr++);
> 
> Is the main problem that they didn't align, or that the index was 
> explicit instead of implicit?

There's no real problem, it's just that
i++, be32_to_cpu and *addr++ is a bit
more common and perhaps more easily read.

The alignment's just a visual nicety.

Ignore it if you choose.

cheers, Joe

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