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authorJames Bottomley <James.Bottomley@HansenPartnership.com>2008-02-19 05:36:56 -0500
committerJens Axboe <jens.axboe@oracle.com>2008-02-19 05:36:56 -0500
commitdde2020754aeb14e17052d61784dcb37f252aac2 (patch)
tree1b6d57c6eff2024fd13e4b3b115d0a6770d8cb80 /drivers/ata/pata_icside.c
parentdb0a2e0099be3a1cff55879225881465f16c67d3 (diff)
libata: eliminate the home grown dma padding in favour of
that provided by the block layer ATA requires that all DMA transfers begin and end on word boundaries. Because of this, a large amount of machinery grew up in ide to adjust scatterlists on this basis. However, as of 2.5, the block layer has a dma_alignment variable which ensures both the beginning and length of a DMA transfer are aligned on the dma_alignment boundary. Although the block layer does adjust the beginning of the transfer to ensure this happens, it doesn't actually adjust the length, it merely makes sure that space is allocated for transfers beyond the declared length. The upshot of this is that scatterlists may be padded to any size between the actual length and the length adjusted to the dma_alignment safely knowing that memory is allocated in this region. Right at the moment, SCSI takes the default dma_aligment which is on a 512 byte boundary. Note that this aligment only applies to transfers coming in from user space. However, since all kernel allocations are automatically aligned on a minimum of 32 byte boundaries, it is safe to adjust them in this manner as well. tj: * Adjusting sg after padding is done in block layer. Make libata set queue alignment correctly for ATAPI devices and drop broken sg mangling from ata_sg_setup(). * Use request->raw_data_len for ATAPI transfer chunk size. * Killed qc->raw_nbytes. * Separated out killing qc->n_iter. Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Diffstat (limited to 'drivers/ata/pata_icside.c')
-rw-r--r--drivers/ata/pata_icside.c8
1 files changed, 0 insertions, 8 deletions
diff --git a/drivers/ata/pata_icside.c b/drivers/ata/pata_icside.c
index 5b8586dac63b..f97068be2d79 100644
--- a/drivers/ata/pata_icside.c
+++ b/drivers/ata/pata_icside.c
@@ -304,12 +304,6 @@ static int icside_dma_init(struct pata_icside_info *info)
304} 304}
305 305
306 306
307static int pata_icside_port_start(struct ata_port *ap)
308{
309 /* No PRD to alloc */
310 return ata_pad_alloc(ap, ap->dev);
311}
312
313static struct scsi_host_template pata_icside_sht = { 307static struct scsi_host_template pata_icside_sht = {
314 .module = THIS_MODULE, 308 .module = THIS_MODULE,
315 .name = DRV_NAME, 309 .name = DRV_NAME,
@@ -389,8 +383,6 @@ static struct ata_port_operations pata_icside_port_ops = {
389 .irq_clear = ata_dummy_noret, 383 .irq_clear = ata_dummy_noret,
390 .irq_on = ata_irq_on, 384 .irq_on = ata_irq_on,
391 385
392 .port_start = pata_icside_port_start,
393
394 .bmdma_stop = pata_icside_bmdma_stop, 386 .bmdma_stop = pata_icside_bmdma_stop,
395 .bmdma_status = pata_icside_bmdma_status, 387 .bmdma_status = pata_icside_bmdma_status,
396}; 388};