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authorRussell King - ARM Linux <linux@arm.linux.org.uk>2011-01-03 22:45:17 +0000
committerDan Williams <dan.j.williams@intel.com>2011-01-04 19:16:14 -0800
commit8087aacda040bdbf84940712d132ce80c30b9d5d (patch)
tree3a59272bc4555eae854a012940a36f80a8f4c1a5 /drivers/dma
parent501e67e82dee68d0a594ec0549f3d6a2943c91f5 (diff)
ARM: PL08x: introduce 'phychan_hold' to hold on to physical channels
Introduce 'phychan_hold' to hold on to physical DMA channels while we're preparing a new descriptor for it. This will be incremented when we allocate a physical channel and set the MUX registers during the preparation of the TXD, and will only be decremented when the TXD is submitted. This prevents the physical channel being given up before the new TXD is placed on the queue. Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk> Acked-by: Linus Walleij <linus.walleij@stericsson.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/amba-pl08x.c11
1 files changed, 11 insertions, 0 deletions
diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c
index 650e2bbc7aad..bf6f7d02c9f6 100644
--- a/drivers/dma/amba-pl08x.c
+++ b/drivers/dma/amba-pl08x.c
@@ -959,6 +959,7 @@ static int prep_phy_channel(struct pl08x_dma_chan *plchan,
ch->signal,
plchan->name);
+ plchan->phychan_hold++;
plchan->phychan = ch;
return 0;
@@ -998,6 +999,8 @@ static dma_cookie_t pl08x_tx_submit(struct dma_async_tx_descriptor *tx)
/* Do this memcpy whenever there is a channel ready */
plchan->state = PL08X_CHAN_WAITING;
plchan->waiting = txd;
+ } else {
+ plchan->phychan_hold--;
}
/* This unlock follows the lock in the prep() function */
@@ -1585,6 +1588,7 @@ static void pl08x_tasklet(unsigned long data)
*/
plchan->lc = txd->tx.cookie;
}
+
/*
* If a new descriptor is queued, set it up
* plchan->at is NULL here
@@ -1598,6 +1602,12 @@ static void pl08x_tasklet(unsigned long data)
list_del(&next->node);
pl08x_start_txd(plchan, next);
+ } else if (plchan->phychan_hold) {
+ /*
+ * This channel is still in use - we have a new txd being
+ * prepared and will soon be queued. Don't give up the
+ * physical channel.
+ */
} else {
struct pl08x_dma_chan *waiting = NULL;
@@ -1625,6 +1635,7 @@ static void pl08x_tasklet(unsigned long data)
ret = prep_phy_channel(waiting,
waiting->waiting);
BUG_ON(ret);
+ waiting->phychan_hold--;
waiting->state = PL08X_CHAN_RUNNING;
waiting->waiting = NULL;
pl08x_issue_pending(&waiting->chan);