013115d90e
Currently, the sense data reporting feature set is enabled for all ATA
devices which supports the feature set (ata_id_has_sense_reporting()),
see ata_dev_config_sense_reporting().
However, even if sense data reporting is enabled, and the device
indicates that sense data is available, the sense data is only fetched
for ATA ZAC devices. For regular ATA devices, the available sense data
is never fetched, it is simply ignored. Instead, libata will use the
ERROR + STATUS fields and map them to a very generic and reduced set
of sense data, see ata_gen_ata_sense() and ata_to_sense_error().
When sense data reporting was first implemented, regular ATA devices
did fetch the sense data from the device. However, this was restricted
to only ATA ZAC devices in commit ca156e006add ("libata: don't request
sense data on !ZAC ATA devices").
With recent changes related to sense data and NCQ autosense, we want
to, once again, fetch the sense data for all ATA devices supporting
sense reporting.
ata_gen_ata_sense() should only be used for devices that don't support
the sense data reporting feature set.
hopefully the features will be more robust this time around.
It is not just ZAC, many new ATA features, e.g. Command Duration
Limits, relies on working NCQ autosense and sense data. Therefore,
it is not really an option to avoid fetching the sense data forever.
If we encounter a device that is misbehaving because the sense data is
actually fetched, then that device should be quirked such that it
never enables the sense data reporting feature set in the first place,
since such a device is obviously not compliant with the specification.
The order in which we will try to add sense data to a scsi_cmnd:
1) NCQ autosense (if supported) - ata_eh_analyze_ncq_error()
2) REQUEST SENSE DATA EXT (if supported) - ata_eh_request_sense()
3) error + status field translation - ata_gen_ata_sense(), called
by ata_scsi_qc_complete() if neither 1) or 2) is supported.
Signed-off-by: Niklas Cassel <niklas.cassel@wdc.com>
Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.