John Clark wrote:
>> We can create a HORKAGE for it. Can you please post the result of
>> "hdparm -I" of the device?
>>
>>
> Tejun,
>
> Here it is:
>
> /dev/nst0:
>
> ATAPI Sequential-access device, with removable media
> Model Number: QUANTUM DAT DAT72-000
Can you please test the attached patch?
Alan, John Clark is reporting that the above tape drive chokes on odd
byte PIO transfer, so the default condition check (qc->nbytes & 15) in
atapi_check_dma() breaks the SATA tape drive, so there's always one
which breaks the other way around. :-(
For the time being, I think the horkage should do. I was wondering
whether you still think we should lift the default mod16 check in
atapi_check_dma().
Thanks.
--
tejun
diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index 1ee9499..e97afce 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -4023,6 +4023,7 @@ static const struct ata_blacklist_entry ata_device_blacklist [] = {
/* Weird ATAPI devices */
{ "TORiSAN DVD-ROM DRD-N216", NULL, ATA_HORKAGE_MAX_SEC_128 },
+ { "QUANTUM DAT DAT72-000", NULL, ATA_HORKAGE_ATAPI_MOD16_DMA },
/* Devices we expect to fail diagnostics */
@@ -4436,7 +4437,8 @@ int atapi_check_dma(struct ata_queued_cmd *qc)
/* Don't allow DMA if it isn't multiple of 16 bytes. Quite a
* few ATAPI devices choke on such DMA requests.
*/
- if (unlikely(qc->nbytes & 15))
+ if (!(qc->dev->horkage & ATA_HORKAGE_ATAPI_MOD16_DMA) &&
+ unlikely(qc->nbytes & 15))
return 1;
if (ap->ops->check_atapi_dma)
diff --git a/include/linux/libata.h b/include/linux/libata.h
index 8bb81d0..9d903b3 100644
--- a/include/linux/libata.h
+++ b/include/linux/libata.h
@@ -371,6 +371,8 @@ enum {
ATA_HORKAGE_IPM = (1 << 7), /* Link PM problems */
ATA_HORKAGE_IVB = (1 << 8), /* cbl det validity bit bugs */
ATA_HORKAGE_STUCK_ERR = (1 << 9), /* stuck ERR on next PACKET */
+ ATA_HORKAGE_ATAPI_MOD16_DMA = (1 << 10), /* use ATAPI DMA for commands
+ not multiple of 16 bytes */
/* DMA mask for user DMA control: User visible values; DO NOT
renumber */
