DT mode

[Richard Moore]

* From the T10 Reflector (t10 at t10.org), posted by:
* Richard Moore <r_moore at qlc.com>
*
Wolfgang,

SPI-3 does allow slower transfer rates in DT mode. The timing requirements
for DT at Fast-10, Fast-20, Fast-40, and Fast-80 rates are all defined in
Table
31 of the spec (p. 85, if you are looking at rev 31a).

I am not aware of any restrictions that would force DT devices to support
all
of the rates so devices that reject slower DT rates are not out of
compliance.

 -- Richard Moore
    QLogic Corp.

>-----Original Message-----
>From: Wolfgang Michel [mailto:wolfgang_michel at vortex.de]
>Sent: Friday, March 17, 2000 9:02 AM
>To: t10 at t10.org
>Subject: DT mode
>
>
>* From the T10 Reflector (t10 at t10.org), posted by:
>* "Wolfgang Michel" <wolfgang_michel at vortex.de>
>*
>
>SPI3 is not very clear about the relationship between DT 
>mode and the transfer rate. So my question is: Are there any 
>restrictions using DT mode (DT_REQ=1) together with any values of the 
>Transfer Period Factor. I have observed that several drives accept 
>PPR messages with DT_REQ=1 only if the transfer period factor is 
>set to Fast-80, i.e. 0x9. If DT with slower transfer rates is 
>allowed, when should then change the data/parity lines (in the 
>middle of the strobe, or after the minimum hold time for the falling 
>edge, or???).
>
>Thanks for the assitance.
>
>Wolfgang
>
>
>
>
>***************************************************
>Wolfgang Michel, Director R&D
>ICP vortex Computersysteme GmbH
>Konrad Zuse Str. 9
>74172 Neckarsulm, Germany
>Tel.: +49-7132-9620-535
>Fax : +49-7132-9620-200
>email: w_michel at vortex.de
>http://www.icp-vortex.com
>http://www.vortex.de
>*************************************************** 
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