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List:       opensolaris-driver-discuss
Subject:    Re: [driver-discuss] WTS PIO on RTL8029AS
From:       "Garrett D'Amore" <gdamore () opensolaris ! org>
Date:       2008-09-08 5:39:32
Message-ID: 48C4BA94.1020803 () opensolaris ! org
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Steven Stallion wrote:
> Garrett D'Amore wrote:
>   
>> Steven Stallion wrote:
>>     
>>>> Perhaps you need to enable 16-bit transfers on the device?
>>>>     
>>>>         
>>> Now that I think about it, probably not. I am trying to read from the
>>> PROM
>>> prior to initializing the device (I believe Masa does something simliar,
>>> except he is explicitly setting WTS - which is probably what I am missing
>>> here).
>>>
>>> Beyond setting WTS on the device, are there any other bits I need to set
>>> WRT PCI? PCI_COMM_IO and PCI_COMM_MAE are set as mentioned in the
>>> specification.
>>>   
>>>       
>> Usually you don't need both PCI_COMM_IO *and* PCI_COMM_MAE... either one
>> or the other is sufficient.  (Which one will depend on the device and
>> what BAR(s) you are using.)
>>     
>
> Gotcha. What is the difference between the two? I have to admit, I'm not
> familiar with BAR either.
>   

BAR == base address register.

IO space is a smaller region of addresses, distinct from the normal 
memory bus -- accessed with special instructions (inb, outb, etc.) 
Memory space is generally accessible using the same instructions used to 
access main memory.

>   
>>>  
>>>       
>>>> Are you making sure that you're using aligned addresses?  (You can not
>>>> do a 16-bit transfer from an odd-byte address on a SPARC system.)
>>>>     
>>>>         
>>> It's on an even offset, but let me double check; I havent checked what
>>> base address was given for the regs map.
>>>   
>>>       
>> PCI base addresses are by definition evenly aligned.  (Actually, they
>> are required to be aligned on 16 byte addresses -- i.e. 128 bit aligned.)
>>
>>     
>
> Gotcha. Setting WTS prior to the read did not have an effect. I'm going
> to try rearranging a few things.
>   

OK.

    -- Garrett
> Steve
>   

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