RE: lack of address frame after reset
I'd like to add my two cents here. Comments below.
At 10:18 AM 0/11/20, Allan Keung wrote:
>Draft D1.1 Clause 33 on P.92 said w.r.t. the address registers -
>"At power up or device reset, the contents of the address register
>are undefined."
>
>After power-up or reset, for the case of an ill-behaved software
>that does not specify at least one address frame first
>before proceeding to a write or read operation, what should be
>the response of a MMD?
>
>I suppose for a write operation, the write will be simply ignored.
>What about a read operation, should the MMD responds with a 0
>(as if addressed to an undefined register) or no response at all
>(as if the wrong port/device is addressed).
As a user and onetime I/O driver writer, I would much prefer that general
reset NOT clear the error registers, to permit post-mortem crash analyses.
This mostly works, although sometimes error registers are scrambled by
whatever bug caused the problem. Correct me if I'm wrong, but I think that
there exist specific commands to clear those registers, so I/O drivers are
able to clear these on init, needed at the very least after a power cycle.
Joe