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libata: fix ATAPI DMA alignment issues

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ATAPI needs to be padded to next 4 byte boundary, if misaligned.

Original work by me, many fixes from Tejun Heo.
This commit is contained in:
Jeff Garzik
2005-10-05 07:13:30 -04:00
parent ed39f731ab
commit cedc9a478d
6 changed files with 173 additions and 40 deletions
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14
drivers/scsi/libata-scsi.c
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@@ -150,10 +150,10 @@ struct ata_queued_cmd *ata_scsi_qc_new(struct ata_port *ap,
qc->scsidone = done;
if (cmd->use_sg) {
qc->sg = (struct scatterlist *) cmd->request_buffer;
qc->__sg = (struct scatterlist *) cmd->request_buffer;
qc->n_elem = cmd->use_sg;
} else {
qc->sg = &qc->sgent;
qc->__sg = &qc->sgent;
qc->n_elem = 1;
}
} else {
@@ -364,6 +364,16 @@ int ata_scsi_slave_config(struct scsi_device *sdev)
*/
blk_queue_max_sectors(sdev->request_queue, 2048);
}
/*
* SATA DMA transfers must be multiples of 4 byte, so
* we need to pad ATAPI transfers using an extra sg.
* Decrement max hw segments accordingly.
*/
if (dev->class == ATA_DEV_ATAPI) {
request_queue_t *q = sdev->request_queue;
blk_queue_max_hw_segments(q, q->max_hw_segments - 1);
}
}
return 0; /* scsi layer doesn't check return value, sigh */