From 91aa5fadb831e7b6ea473a526a6b49c6dc4819ce Mon Sep 17 00:00:00 2001 From: Russell King - ARM Linux Date: Mon, 3 Jan 2011 22:31:04 +0000 Subject: [PATCH] ARM: PL08x: fix atomic_t usage and tx_submit() return value range The last_issued variable uses an atomic type, which is only incremented inside a protected region, and then read. Everywhere else only reads the value, so it isn't using atomic_t correctly, and it doesn't even need to. Moreover, the DMA engine code provides us with a variable for this already - chan.cookie. Use chan.cookie instead. Also, avoid negative dma_cookie_t values - negative returns from tx_submit() mean failure, yet in reality we always succeed. Restart from cookie 1, just like other DMA engine drivers do. Signed-off-by: Russell King Acked-by: Linus Walleij Signed-off-by: Dan Williams --- drivers/dma/amba-pl08x.c | 18 +++++++++--------- include/linux/amba/pl08x.h | 1 - 2 files changed, 9 insertions(+), 10 deletions(-) diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c index 0809810..5d9a156 100644 --- a/drivers/dma/amba-pl08x.c +++ b/drivers/dma/amba-pl08x.c @@ -74,7 +74,6 @@ #include #include #include -#include #include #include @@ -1082,8 +1081,10 @@ static dma_cookie_t pl08x_tx_submit(struct dma_async_tx_descriptor *tx) { struct pl08x_dma_chan *plchan = to_pl08x_chan(tx->chan); - atomic_inc(&plchan->last_issued); - tx->cookie = atomic_read(&plchan->last_issued); + plchan->chan.cookie += 1; + if (plchan->chan.cookie < 0) + plchan->chan.cookie = 1; + tx->cookie = plchan->chan.cookie; /* This unlock follows the lock in the prep() function */ spin_unlock_irqrestore(&plchan->lock, plchan->lockflags); @@ -1115,7 +1116,7 @@ pl08x_dma_tx_status(struct dma_chan *chan, enum dma_status ret; u32 bytesleft = 0; - last_used = atomic_read(&plchan->last_issued); + last_used = plchan->chan.cookie; last_complete = plchan->lc; ret = dma_async_is_complete(cookie, last_complete, last_used); @@ -1131,7 +1132,7 @@ pl08x_dma_tx_status(struct dma_chan *chan, /* * This cookie not complete yet */ - last_used = atomic_read(&plchan->last_issued); + last_used = plchan->chan.cookie; last_complete = plchan->lc; /* Get number of bytes left in the active transactions and queue */ @@ -1641,8 +1642,7 @@ static void pl08x_tasklet(unsigned long data) /* * Update last completed */ - plchan->lc = - (plchan->at->tx.cookie); + plchan->lc = plchan->at->tx.cookie; /* * Callback to signal completion @@ -1820,8 +1820,8 @@ static int pl08x_dma_init_virtual_channels(struct pl08x_driver_data *pl08x, chan->name); chan->chan.device = dmadev; - atomic_set(&chan->last_issued, 0); - chan->lc = atomic_read(&chan->last_issued); + chan->chan.cookie = 0; + chan->lc = 0; spin_lock_init(&chan->lock); INIT_LIST_HEAD(&chan->desc_list); diff --git a/include/linux/amba/pl08x.h b/include/linux/amba/pl08x.h index 521a0f8..4ae62b4 100644 --- a/include/linux/amba/pl08x.h +++ b/include/linux/amba/pl08x.h @@ -174,7 +174,6 @@ struct pl08x_dma_chan { struct pl08x_channel_data *cd; dma_addr_t runtime_addr; enum dma_data_direction runtime_direction; - atomic_t last_issued; dma_cookie_t lc; struct list_head desc_list; struct pl08x_txd *at; -- 2.7.4