Hi all,
This is v4, addressing review feedback from Damien Le Moal and Hannes
Reinecke on v3.
This series gives libata support for ATAPI devices with multiple LUNs,
such as the Panasonic PD-1 PD/CD combo drive. This exposes both the
CD-ROM and rewritable PD optical interfaces: CD-ROM as LUN 0 and PD
as LUN 1.
libata has never supported multi-LUN ATAPI. This series adds support
by fixing the following limitations:
1. shost->max_lun is hardcoded to 1 in ata_scsi_add_hosts(), preventing
the SCSI layer from probing any LUN beyond 0.
2. __ata_scsi_find_dev() rejects all commands where scsidev->lun != 0,
returning NULL and resulting in DID_BAD_TARGET.
3. The SCSI-2 CDB LUN field (byte 1, bits 7:5) is never populated.
ATAPI tunnels SCSI commands over the ATA PACKET interface, and the
transport-layer LUN addressing used by SPC-3+ is not available.
Older multi-LUN ATAPI devices rely on this CDB field to route
commands to the correct LUN.
4. ata_scsi_scan_host() only calls __scsi_add_device() for LUN 0,
never probing additional LUNs even when the SCSI device info table
would indicate the device supports them.
5. dev->sdev is a single pointer, but multi-LUN ATAPI puts multiple
sdevs behind one ata_device. Every call to ata_scsi_dev_config()
overwrote the pointer, and ata_scsi_sdev_destroy() tore down the
entire ATA device whenever any sdev was destroyed -- so removing a
spurious LUN result during scanning would kill the whole port, and
the other users of dev->sdev (scsi_remove_device in
ata_port_detach(), ACPI uevents, zpodd, media-change notify,
suspend/resume rescan) could only ever see one LUN.
Changes from v3:
- 1/7 unchanged; carries Hannes' Reviewed-by from v2.
- 2/7 (sdev array): added a per-device dev->nr_luns field so the
common single-LUN case iterates one slot rather than ATAPI_MAX_LUN
(8). Added an inline ata_dev_scsi_device(dev, lun) helper with a
WARN_ON_ONCE(lun >= dev->nr_luns) bounds check, and converted the
hardcoded LUN-0 references in libata-acpi (uevent kobj),
libata-zpodd (disk events, wake notify), and the door-lock and
OF-node paths in libata-scsi to use it. Hannes' v2 Reviewed-by
has been dropped given the scope of the rework.
- 3/7 (LUN routing): hoisted the non-zero LUN handling to the top of
__ata_scsi_find_dev() so the original channel/id rejection logic
is left structurally unchanged. Replaced the bare "lun >= 8" gate
in atapi_xlat() with WARN_ON_ONCE(lun >= dev->nr_luns); the SCSI
layer caps lun at shost->max_lun (<= ATAPI_MAX_LUN), so this
should never trigger in practice.
- 4/7 (BLIST_NO_LUN_1F): use sdev->sdev_bflags (just assigned)
rather than re-dereferencing *bflags, and dropped a stray blank
line. Picked up Reviewed-by tags from Damien and Hannes.
- 5/7 (probe extra LUNs): dropped the introduced inner { } scope
around sdev so the declaration sits at its original spot at the
top of the loop body. Bump dev->nr_luns to the host's max_lun
before calling scsi_scan_target() so the probe INQUIRYs to LUN > 0
are accepted by atapi_xlat(). Stale "see patch X" cross-references
have been removed from the changelog.
- 6/7 (COMPAQ PD-1): unchanged; picked up Reviewed-by tags from
Damien and Hannes.
- 7/7 (MATSHITA + NEC PD-1): unchanged; picked up Reviewed-by tag
from Damien. Kept as a separate patch from 6/7: the variants are
untested (the author only has the COMPAQ unit), and being a
standalone patch lets maintainers drop or hold it independently
from the rest of the series.
The series is split as:
1/7: libata-scsi: add libata.atapi_max_lun module parameter.
2/7: libata-scsi: convert dev->sdev to a per-LUN array, add
dev->nr_luns and the ata_dev_scsi_device() helper, and update
every caller.
3/7: libata-scsi: relax __ata_scsi_find_dev() to accept non-zero LUN
for ATAPI devices, and encode the LUN in CDB byte 1 bits 7:5.
4/7: scsi: add a BLIST_NO_LUN_1F blacklist flag, which sets
scsi_target.pdt_1f_for_no_lun for matching devices so that
PDT 0x1f / PQ 0 INQUIRY responses are treated as "LUN not
present" and silently skipped.
5/7: libata-scsi: after adding LUN 0, trigger scsi_scan_target() for
BLIST_FORCELUN ATAPI devices only. Single-LUN devices are
completely unaffected.
6/7: scsi_devinfo: add the COMPAQ-branded variant of the PD-1 to the
device info table with BLIST_FORCELUN | BLIST_SINGLELUN |
BLIST_NO_LUN_1F.
7/7: scsi_devinfo: extend BLIST_NO_LUN_1F to the MATSHITA and NEC
PD-1 variants. Untested on those OEM units (the author only
has the COMPAQ-branded drive), but all three appear to use the
same Panasonic LF-1095/LF-1195 mechanism and firmware family,
so the quirk is expected to apply equally. Kept separate so
it can be dropped independently if confirmation on MATSHITA or
NEC hardware is preferred.
Tested on a Panasonic LF-1195C PD/CD (Compaq branded) attached to an
ata_piix host on i686, kernel 7.0.0-rc7+, with libata.atapi_max_lun=7.
Both LUNs enumerate correctly: the CD-ROM as sr0 and the PD as sda.
Reads from each device succeed against the appropriate media.
Non-responding LUNs are silently skipped (no spurious "No Device"
entries in dmesg). An iHAS124 DVD writer on the same machine
(single-LUN, no BLIST_FORCELUN entry) is unaffected: only LUN 0 is
scanned.
Two known limitations around media-change detection on multi-LUN
ATAPI devices with a shared physical media slot (e.g. PD/CD combos
flagged BLIST_SINGLELUN):
1. The block layer disables in-kernel polling by default
(block.events_dfl_poll_msecs defaults to 0). Without polling,
sd_check_events never runs and media insertion on the PD LUN is
not detected automatically. sr_mod is unaffected because it
re-reads the TOC on every open.
Workaround -- either globally via kernel boot parameter:
block.events_dfl_poll_msecs=2000
or per-device via udev rule:
ACTION=="add", KERNEL=="sd*", \
ATTRS{vendor}=="COMPAQ ", ATTRS{model}=="PD-1*", \
ATTR{events_poll_msecs}="2000"
Even with polling enabled the sd path does not always pick up
fresh media on this firmware; `blockdev --rereadpt /dev/sdX`
reliably forces a revalidate and proves the libata routing
itself is correct.
2. Media-change sense is not propagated across sibling LUNs. When
one LUN reports UNIT ATTENTION (ASC 0x28 or 0x3A), the other LUNs
are not notified. With polling enabled, sd_check_events detects
the change independently on each LUN via TUR, so this is mainly a
latency issue rather than a functional one. A follow-up to
propagate media-change events to sibling LUNs in
atapi_qc_complete is straightforward but deferred to keep this
series focused on the LUN-scanning core.
Suspend/resume with multi-LUN ATAPI attached has not yet been tested;
this is on the list. ata_scsi_dev_rescan iterates all populated LUN
slots, and the SCSI layer's host-level suspend tracking already
serialises port quiesce, so no additional per-LUN suspend counting
is needed in libata.
Comments and suggestions welcome.
Phil Pemberton (7):
ata: libata-scsi: add atapi_max_lun module parameter
ata: libata-scsi: convert dev->sdev to per-LUN array
ata: libata-scsi: route non-zero LUN commands for multi-LUN ATAPI
scsi: add BLIST_NO_LUN_1F blacklist flag
ata: libata-scsi: probe additional LUNs for multi-LUN ATAPI devices
scsi: scsi_devinfo: add COMPAQ PD-1 multi-LUN ATAPI device quirk
scsi: scsi_devinfo: extend BLIST_NO_LUN_1F to MATSHITA and NEC PD-1
variants
drivers/ata/libata-acpi.c | 6 +-
drivers/ata/libata-core.c | 16 ++-
drivers/ata/libata-scsi.c | 208 +++++++++++++++++++++++-------------
drivers/ata/libata-zpodd.c | 6 +-
drivers/ata/libata.h | 1 +
drivers/scsi/scsi_devinfo.c | 8 +-
drivers/scsi/scsi_scan.c | 2 +
include/linux/libata.h | 12 ++-
include/scsi/scsi_devinfo.h | 6 +-
9 files changed, 175 insertions(+), 90 deletions(-)
--
2.43.0