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Date:      Fri, 29 Aug 2008 14:02:51 -0700
From:      Sean Bruno <sbruno@miralink.com>
To:        Dieter <freebsd@sopwith.solgatos.com>
Cc:        freebsd-firewire@freebsd.org
Subject:   Re: This is where I'm going with fwcontrol
Message-ID:  <48B863FB.10202@miralink.com>
In-Reply-To: <200808292021.UAA25442@sopwith.solgatos.com>
References:  <200808292021.UAA25442@sopwith.solgatos.com>

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Dieter wrote:
>>> Should
>>>
>>>   
>>>       
>>>> Message ID  Root ID  R T Gap Count
>>>>    00(2 bits)  (5 bits)    1 1    (6 bits)
>>>>     
>>>>         
>>>  
>>> be
>>>
>>> Message ID   Root ID    R  T   Gap Count
>>> 00(2 bits)   (6 bits)   1  1   (6 bits)
>>>
>>> send_phy_config() ANDs root_node with 0x3f, and the
>>> "Physical ID" field in the controller register is
>>> 6 bits.
>>>   
>>>       
>> Well, according to the 1394 documentation, no.  The root ID is 
>> definitely 5 bits.
>>
>> The gap count is also 5 bits, I must have mis-counted.  So, really it 
>> should be:
>>
>> Message ID   Root ID    R  T   Gap Count
>> 00(2 bits)   (5 bits)   1  1   (5 bits)
>>     
>
> Looking at "Table 5. PHY Register Map" in the VIA controller datasheet
> (page 24 of the pdf)
> http://www.datasheetarchive.com/pdf-datasheets/Datasheets-6/DSA-113181.pdf
>
> the "Physical ID" field is 6 bits, as is the "Gap Count" field.
> I don't have the IEEE documentation, so I'll have to assume
> you are correct about it saying 5 bits.  So why doesn't the
> controller datasheet agree with the IEEE doc?  Granted one is
> a controller register and the other is a packet, but I'd
> expect these individual fields to be the same size.
>
>   
>> This means that the Root ID and the Gap Count cannot exceed 0x3f(63).
>>     
>
> That's 6 bits.  5 bits would be 0x1f = 31 decimal.
>
>   
Huh....I seem to be having some kind of wierd PDF rendering issue. 

Ok, so looking at the document in another application(not acroread),
the Node ID is 6 bits, the Gap Count is 6 bits.  I'm the crazy one I guess.

Wierd.
>> So, the masking
>> of the values instead of generating and error seems wrong to me.  I'm 
>> going to put in error checking
>> to make sure the values comply with the specification and document the 
>> correct values in the man page
>> and the comments of the code.
>>     
>
> Sounds good.
>   


-- 
Sean Bruno
MiraLink Corporation
6015 NE 80th Ave, Ste 100
Portland, OR 97218
Phone 503-621-5143
Fax 503-621-5199
MSN: sbruno@miralink.com
Google:  seanwbruno@gmail.com
Yahoo:  sean_bruno@yahoo.com




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