Re: [PATCH 1/4] netdev/phy: Handle IEEE802.3 clause 45 Ethernet PHYs

[David Daney <ddaney.cavm@xxxxxxxxx>]

On 06/25/2012 03:34 PM, David Miller wrote:
> From: David Daney<ddaney.cavm@xxxxxxxxx>
> Date: Fri, 22 Jun 2012 17:24:13 -0700
>
> > From: David Daney<david.daney@xxxxxxxxxx>
> >
> > The IEEE802.3 clause 45 MDIO bus protocol allows for directly
> > addressing PHY registers using a 21 bit address, and is used by many
> > 10G Ethernet PHYS.  Already existing is the ability of MDIO bus
> > drivers to use clause 45, with the MII_ADDR_C45 flag.  Here we add
> > struct phy_c45_device_ids to hold the device identifier registers
> > present in clause 45. struct phy_device gets a couple of new fields:
> > c45_ids to hold the identifiers and is_c45 to signal that it is clause
> > 45.
> >
> > Normally the MII_ADDR_C45 flag is ORed with the register address to
> > indicate a clause 45 transaction.  Here we also use this flag in the
> > *device* address passed to get_phy_device() to indicate that probing
> > should be done with clause 45 transactions.
> >
> > EXPORT phy_device_create() so that the follow-on patch to of_mdio.c
> > can use it to create phy devices for PHYs, that have non-standard
> > device identifier registers, based on the device tree bindings.
> >
> > Signed-off-by: David Daney<david.daney@xxxxxxxxxx>
>
> I see no value in having two ways to say that clause-45 transactions
> should be used.
>
> Either make it a PHY device attribute, or specify it in the address
> in the register accesses, but not both.

Do you realize that at the time get_phy_device() is called, there is no 
PHY device?  So there can be no attribute, nor are we passing a register 
address.  Neither of these suggestions apply to this situation.

We need to know a priori if it is c22 or c45.  So we need to communicate 
the type somehow to get_phy_device().  I chose an unused bit in the addr 
parameter to do this, another option would be to add a separate 
parameter to get_phy_device() specifying the type.



> Also your patch is full of coding style errors, I simply couldn't
> stomache applying this even if I agreed with the substance of the
> changes:
>
> > +	     i<  ARRAY_SIZE(c45_ids->device_ids)&&
> > +		     c45_ids->devices_in_package == 0;
>
> c45_ids on the second line should line up with the initial 'i'
> on the first line.
>
> > +		c45_ids->devices_in_package = (phy_reg&  0xffff)<<  16;
> > +
> > +
> > +		reg_addr = MII_ADDR_C45 | i<<  16 | 5;
>
> There is not reason in the world to have two empty lines there, it
> looks awful.

OK, I will fix those...

> > +		/*
> > +		 * If mostly Fs, there is no device there,
> > +		 * let's get out of here.
> > +		 */
>
> Format comments:
>
> 	/* Like
> 	 * this.
> 	 */
>
> Not.
>
> 	/*
> 	 * Like
> 	 * this.
> 	 */

... and this one too I guess.  Really you and Linus should come to a 
consensus on this one.

[...]
> > +/*
> > + * phy_c45_device_ids: 802.3-c45 Device Identifiers
> > + *
> > + * devices_in_package: Bit vector of devices present.
> > + * device_ids: The device identifer for each present device.
> > + */
>
> If you're going to list the struct members use the correct kerneldoc
> format to do so.

OK.

David Daney