Re: Scary Intel SATA problem: "frozen"

[Sergei Shtylyov <sshtylyov@ru.mvista.com>]

Hello.

Eric D. Mudama wrote:
>> > Bit #4, when actually implemented, is a rotational seek indicator,
>> > which can be used for timing purposes.

>>     Hm, I thought it was DSC (drive seek complete) set by the SEEK 
>> command
>> completion, and it's always implemented. Didn't you mean IDX (bit 1, 
>> IIRC)?

> 0x50 is the standard, non queueing "device is ready" status.  It used
> to have those special meanings, but they're pretty obsolete today as I
> understand it.

    Erm, some status bits maybe obsolete but I've never heard that the status 
*values* were specified to mean anything special anywhere...

> 0x40 is used for queueing, because bit 4 was the service bit for PATA TCQ.

   I know. This meaning (SERVICE) actualy came from ATAPI

>> > But when BUSY (bit #7) is set, the rest are generally nonsense.

>>     Indeed...

>> WBR, Sergei

> Typically, 0x80 as the busy state indicates the device is in POR
> reset.  Once the firmware is up and running in the device, it often
> switches from 0x80 to 0xD0 during POR.

    Oh, I guess it's completely up to the disk makers what other status to 
show with BSY=1.

> 0xD0 is the busy state you'd get to if you were 0x50 and received a
> command, so this is reported typically after the device is up and
> running.

> 0x7F usually is hardware indicating nothing is attached to the port,
> and isn't supposed to infer a non-busy state.

    Ha, *never* seen that one. It's has always been 0xFF since PC people 
didn't ever bother themselves with silly pulldowns. :-)

> You're right, while not meaningful according to spec, you can derive
> some information from the reported status even when you're only
> supposed to look at one bit.

   Well, to some extent...

WBR, Sergei