Messages in this thread | | | Date | Wed, 13 Jun 2007 14:40:45 -0400 | From | Mark Lord <> | Subject | Re: libata passthru: support PIO multi commands |
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Albert Lee wrote: > .. > It looks like the ATA passthru commands contain more information than > what libata needs to execute a command. > > e.g. protocol number: > libata could possibly infer the protocol from the command opcode. > > e.g. multi_count: > libata caches dev->multi_count. Passing multi_count along with > each passthru command looks useless for libata. > > e.g. t_dir: > libata could possible infer the direction from the command opcode > or from the protocol number (e.g. 4: PIO_IN / 5: PIO_OUT).
I wonder if the *intent* of the specification was that the low-level driver should perform whatever setup is necessary to issue the command as given.
So if the command specifies a multcount of 8, then the LLD should issue the appropriate initialization commands to use a multcount of 8, and then issue the given R/W MULT command, and then perhaps reset the multcount back to what it was normally (beforehand) ?
Ditto for the others.
I am *not* proposing that we actually do it this way, but rather just suggesting a possible rationale.
What does the SAT spec say? Any further hints as to the intent?
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