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| author | Clemens Ladisch <clemens@ladisch.de> | 2012-05-18 22:26:21 +0200 |
|---|---|---|
| committer | Stefan Richter <stefanr@s5r6.in-berlin.de> | 2012-05-21 21:49:44 +0200 |
| commit | 26c72e22c94fbc28604c94e3a96fdae9c6fd0a42 (patch) | |
| tree | 9897f59fef9034951ce4b236da8820ea7e38a07a /drivers/firewire/sbp2.c | |
| parent | firewire: sbp2: remove superfluous blk_queue_max_segment_size() call (diff) | |
| download | linux-26c72e22c94fbc28604c94e3a96fdae9c6fd0a42.tar.xz linux-26c72e22c94fbc28604c94e3a96fdae9c6fd0a42.zip | |
firewire: sbp2: document the absence of alignment requirements
The SBP-2/3 specifications do not require any alignment of data
buffers; only their own data structures need to be quadlet-aligned
[SR: or octlet-aligned].
Fix the comments to reflect this, but leave the actual alignment at
32 bits to avoid theoretical problems with target implementations
that might handle this incorrectly.
Signed-off-by: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Diffstat (limited to 'drivers/firewire/sbp2.c')
| -rw-r--r-- | drivers/firewire/sbp2.c | 10 |
1 files changed, 6 insertions, 4 deletions
diff --git a/drivers/firewire/sbp2.c b/drivers/firewire/sbp2.c index 1f888f3ef7ae..1162d6b3bf85 100644 --- a/drivers/firewire/sbp2.c +++ b/drivers/firewire/sbp2.c @@ -207,9 +207,8 @@ static const struct device *lu_dev(const struct sbp2_logical_unit *lu) #define SBP2_MAX_CDB_SIZE 16 /* - * The default maximum s/g segment size of a FireWire controller is - * usually 0x10000, but SBP-2 only allows 0xffff. Since buffers have to - * be quadlet-aligned, we set the length limit to 0xffff & ~3. + * The maximum SBP-2 data buffer size is 0xffff. We quadlet-align this + * for compatibility with earlier versions of this driver. */ #define SBP2_MAX_SEG_SIZE 0xfffc @@ -1530,7 +1529,10 @@ static int sbp2_scsi_slave_alloc(struct scsi_device *sdev) sdev->allow_restart = 1; - /* SBP-2 requires quadlet alignment of the data buffers. */ + /* + * SBP-2 does not require any alignment, but we set it anyway + * for compatibility with earlier versions of this driver. + */ blk_queue_update_dma_alignment(sdev->request_queue, 4 - 1); if (lu->tgt->workarounds & SBP2_WORKAROUND_INQUIRY_36) |