[PATCH 19/29] ioat1: trim ioat_dma_desc_sw

Dan Williams
2009-09-04T02:35:37Z

Save 4 bytes per software descriptor by transmitting tx_cnt in an unused
portion of the hardware descriptor.

Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
drivers/dma/ioat/dma.c | 4 ++--
drivers/dma/ioat/dma.h | 2 --
drivers/dma/ioat/hw.h | 6 +++++-
3 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/drivers/dma/ioat/dma.c b/drivers/dma/ioat/dma.c
index abc96c4..f59b6f4 100644
--- a/drivers/dma/ioat/dma.c
+++ b/drivers/dma/ioat/dma.c
@@ -396,7 +396,7 @@ static dma_cookie_t ioat1_tx_submit(struct dma_async_tx_descriptor *tx)
dump_desc_dbg(ioat, chain_tail);
dump_desc_dbg(ioat, first);

- ioat->pending += desc->tx_cnt;
+ ioat->pending += desc->hw->tx_cnt;
if (ioat->pending >= ioat_pending_level)
__ioat1_dma_memcpy_issue_pending(ioat);
spin_unlock_bh(&ioat->desc_lock);
@@ -655,11 +655,11 @@ ioat1_dma_prep_memcpy(struct dma_chan *c, dma_addr_t dma_dest,
spin_unlock_bh(&ioat->desc_lock);

desc->txd.flags = flags;
- desc->tx_cnt = tx_cnt;
desc->len = total_len;
list_splice(&chain, &desc->txd.tx_list);
hw->ctl_f.int_en = !!(flags & DMA_PREP_INTERRUPT);
hw->ctl_f.compl_write = 1;
+ hw->tx_cnt = tx_cnt;
dump_desc_dbg(ioat, desc);

return &desc->txd;
diff --git a/drivers/dma/ioat/dma.h b/drivers/dma/ioat/dma.h
index e47083b..ec851cf 100644
--- a/drivers/dma/ioat/dma.h
+++ b/drivers/dma/ioat/dma.h
@@ -165,14 +165,12 @@ ioat_is_complete(struct dma_chan *c, dma_cookie_t cookie,
* @hw: hardware DMA descriptor
* @node: this descriptor will either be on the free list,
* or attached to a transaction list (async_tx.tx_list)
- * @tx_cnt: number of descriptors required to complete the transaction
* @txd: the generic software descriptor for all engines
* @id: identifier for debug
*/
struct ioat_desc_sw {
struct ioat_dma_descriptor *hw;
struct list_head node;
- int tx_cnt;
size_t len;
struct dma_async_tx_descriptor txd;
#ifdef DEBUG
diff --git a/drivers/dma/ioat/hw.h b/drivers/dma/ioat/hw.h
index e13f3ed..7481fb1 100644
--- a/drivers/dma/ioat/hw.h
+++ b/drivers/dma/ioat/hw.h
@@ -63,7 +63,11 @@ struct ioat_dma_descriptor {
uint64_t next;
uint64_t rsv1;
uint64_t rsv2;
- uint64_t user1;
+ /* store some driver data in an unused portion of the descriptor */
+ union {
+ uint64_t user1;
+ uint64_t tx_cnt;
+ };
uint64_t user2;
};
#endif