From 8087aacda040bdbf84940712d132ce80c30b9d5d Mon Sep 17 00:00:00 2001 From: Russell King - ARM Linux Date: Mon, 3 Jan 2011 22:45:17 +0000 Subject: 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 Acked-by: Linus Walleij Signed-off-by: Dan Williams --- drivers/dma/amba-pl08x.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'drivers') diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c index 650e2bb..bf6f7d0 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); -- cgit v1.1