[s]sd-config-list version 2 and retry count tuning [PSARC/2007/505 FastTrack timeout 09/11/2007]

[yu larry liu]

>> We didn't change the syntax for property encoding from version 1.  I 
>> agree with you it is error prone. But it is simple and efficient. And it 
>> leaves door open to future version development. If splitting the 
>> properties, it will be complex for the combination of VID, PID and 
>> single property.  Any suggestion?
>>     
>
> I'm not 100% familiar with the constraints on entries in driver.conf
> files but an attribute=value encoding like:
>
> t4-data="nonvolatile-cache=1,timeout-retry-count=42,min-throttle=2,max-throttle=17";
>
> would be way better than
>
> t4-data=2,0x303,2,17,0,0,0,0,0,0,0,42,1
>
> (I *think* I got that right).
>
> (Maybe the answer here is to provide tools or scripts to construct and
> decode these entries, which wouldn't be this project but a worthy
> followon).  
>
>   

Yes, we could do this in sd.conf. And this seems much more friendly 
though not quite easy for implementation.

However, both sd.conf and st.conf, (I believe there might be some other 
driver.conf) have the same situation. Similar syntax is used in st.conf 
when adding support to new tape device. So, actually, we want a generic 
friendly way in driver.conf, not specific in sd.conf, for property 
definition:
for a given device type, identified by a 'VID + PID' combination, we 
would like the ability to define multiple properties associated with 
such device type; a version number is also desirable here for future 
upgrade.

It is probably out of the scope of this project but worthy to dig further.
>> In version 2, we plan to only support those properties defined in 
>> sd_tunables table which is commonly used.
>>     
>
> The word "support" is ambiguous and should generally be avoided in
> specifications.  I think you mean "allow".  
>
>   
Yes. Thanks for point it out. I will correct it.
> BTW, it looks like the spec is missing a reference to 
> 2007/053 (for the "non-volatile cache" bit) and perhaps a few others.
>   
Will check and add.

Thanks
Larry