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RE: Clause 33 (MDC/MDIO) questions


Based on your responses to my earlier comments in regard to the address
register, I
thought you were going to change the description of how the addressing
worked to
make the following principles clear:

  There is an address stored in the device.

  Once an address frame has been received by a device, that address stays in
the device
  until another address frame to the device overwrites it or an increment 
  frame increments it (or possibly the chip is reset - we didn't discuss
  Then the newly written address or the incremented value of the address
takes its

  The address is not changed by address operations to other devices sharing

Once that has been explained, saying "It is recommended that the address
frame is followed by its
associated write, ..." seems unnecessary and confusing. After all, it
clearly doesn't work
for the write or read to precede the address frame. Once the address frame
has written the
address, bunches of writes and reads may occur to that and following
registers without
an intervening write.

I recommend deleting the sentence.


----- Original Message ----- 
From: "Edward Turner" <Edward_Turner@xxxxxxxxxxxx>
To: <stds-802-3-hssg@xxxxxxxx>
Sent: Friday, October 20, 2000 3:35 AM
Subject: Re: Clause 33 (MDC/MDIO) questions

> Louis,
> I'm going to remove the word 'immediately' from the next draft.
> You can interpret the word 'should' as 'is recommended that', so the
> can also be read as 'It is recommended that the address frame is followed
by its
> associated write, ...'.
> There is no IFG defined for the MDIO interface.
> Sending address frames back to back will not break anything.  Each time an
> address frame is received it overwrites the MDIO device's address
register.  The
> address used for a transaction will be whatever is held in this address
> register.
> Regards
> Ed
> Louis Lin <louislin@xxxxxxxx> on 19/10/2000 23:39:54
> Sent by:  Louis Lin <louislin@xxxxxxxx>
> To:   stds-802-3-hssg@xxxxxxxx
> cc:    (Edward Turner/GB/3Com)
> Subject:  Clause 33 (MDC/MDIO) questions
> Hi,
> On page 84. second section after the table 33-21.
> 'An address frame should be followed "IMMEDIATELY" by its
> associated write, ..........'
> Can you define "immediately"? is there a max IFG ?
> Or it's just saying the PHY device is expecting a data frame after
> an address frame?
> Will it break anything if we send two address frames without any
> data frame in between?
> I expect that the second register address will overwrite the first
> register address in the PHY's local address table without breaking
> anything.
> Thanks,
> Louis Lin