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SubjectRe: [PATCH 1/4] netdev/phy: Handle IEEE802.3 clause 45 Ethernet PHYs
On 06/25/2012 03:34 PM, David Miller wrote:
> From: David Daney<ddaney.cavm@gmail.com>
> Date: Fri, 22 Jun 2012 17:24:13 -0700
>
>> From: David Daney<david.daney@cavium.com>
>>
>> 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@cavium.com>
>
> 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


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