Jeff Garzik wrote:
> Brian King wrote:
>> Going along with that argument, there's really no good reason for
>> libata to be playing games with scsi_host->max_cmd_len based on
>> the attached devices.
>
> If both host controller and device support 16-byte CDB, it should not be
> limited to 12 bytes.
Agreed.
> libata is not "playing games", just exporting what the hardware supports
> as best the API allows. It needs to support 16-byte CDBs for the same
> reason any SCSI LLDD supports 16-byte CDBs.
>
> Remember ATAPI<->SCSI bridges exist, thus any SCSI disk can appear
> attached to ATAPI.
The libata code in question is the code that changes
scsi_host->max_cmd_len based on what the attached devices support.
I propose the following patch. This patch is untested.
--
Brian King
eServer Storage I/O
IBM Linux Technology Center
Signed-off-by: Brian King <brking@xxxxxxxxxx>
---
libata-dev-bjking1/drivers/scsi/libata-core.c | 8 +-------
1 files changed, 1 insertion(+), 7 deletions(-)
diff -puN drivers/scsi/libata-core.c~libata_max_cmd_len drivers/scsi/libata-core.c
--- libata-dev/drivers/scsi/libata-core.c~libata_max_cmd_len 2006-04-28 16:34:16.000000000 -0500
+++ libata-dev-bjking1/drivers/scsi/libata-core.c 2006-04-28 16:34:40.000000000 -0500
@@ -1328,12 +1328,6 @@ static int ata_dev_configure(struct ata_
ap->id, dev->devno, ata_mode_string(xfer_mask));
}
- ap->host->max_cmd_len = 0;
- for (i = 0; i < ATA_MAX_DEVICES; i++)
- ap->host->max_cmd_len = max_t(unsigned int,
- ap->host->max_cmd_len,
- ap->device[i].cdb_len);
-
/* limit bridge transfers to udma5, 200 sectors */
if (ata_dev_knobble(ap, dev)) {
if (print_info)
@@ -4573,7 +4567,7 @@ static void ata_host_init(struct ata_por
host->max_lun = 1;
host->max_channel = 1;
host->unique_id = ata_unique_id++;
- host->max_cmd_len = 12;
+ host->max_cmd_len = ATAPI_CDB_LEN;
ap->flags = ATA_FLAG_DISABLED;
ap->id = host->unique_id;
_
