-----------------------
Internal commands
- First, qc is allocated and initialized using :c:func:`ata_qc_new_init`.
- Although :c:func:`ata_qc_new_init` doesn't implement any wait or retry
- mechanism when qc is not available, internal commands are currently
- issued only during initialization and error recovery, so no other
- command is active and allocation is guaranteed to succeed.
-
Once allocated qc's taskfile is initialized for the command to be
executed. qc currently has two mechanisms to notify completion. One
is via ``qc->complete_fn()`` callback and the other is completion
translated. No qc is involved in processing a simulated scmd. The
result is computed right away and the scmd is completed.
- For a translated scmd, :c:func:`ata_qc_new_init` is invoked to allocate a
- qc and the scmd is translated into the qc. SCSI midlayer's
- completion notification function pointer is stored into
- ``qc->scsidone``.
-
``qc->complete_fn()`` callback is used for completion notification. ATA
commands use :c:func:`ata_scsi_qc_complete` while ATAPI commands use
:c:func:`atapi_qc_complete`. Both functions end up calling ``qc->scsidone``