diff options
| author | Russell King - ARM Linux <linux@arm.linux.org.uk> | 2011-01-27 12:32:53 +0000 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2011-01-30 22:00:48 -0800 |
| commit | fb526210b2b961b5d590b89fd8f45c0ca5769688 (patch) | |
| tree | 4998a89c11eed597b3197d013ff7b558c9566f2d /drivers | |
| parent | d718f4ebddcb0bebdbf771a6672756b666e5c31b (diff) | |
DMA: PL08x: fix infinite wait when terminating transfers
If we try to pause a channel when terminating a transfer, we could end
up spinning for it to become inactive indefinitely, and can result in
an uninterruptible wait requiring a reset to recover from.
Terminating a transfer is supposed to take effect immediately, but may
result in data loss.
To make this clear, rename the function to pl08x_terminate_phy_chan().
Also, make sure it is always consistently called - with the spinlock
held and IRQs disabled, and ensure that the TC and ERR interrupt status
is always cleared.
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')
| -rw-r--r-- | drivers/dma/amba-pl08x.c | 32 |
1 files changed, 18 insertions, 14 deletions
diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c index 297f48b0cba..8321a3997c9 100644 --- a/drivers/dma/amba-pl08x.c +++ b/drivers/dma/amba-pl08x.c @@ -267,19 +267,24 @@ static void pl08x_resume_phy_chan(struct pl08x_phy_chan *ch) } -/* Stops the channel */ -static void pl08x_stop_phy_chan(struct pl08x_phy_chan *ch) +/* + * pl08x_terminate_phy_chan() stops the channel, clears the FIFO and + * clears any pending interrupt status. This should not be used for + * an on-going transfer, but as a method of shutting down a channel + * (eg, when it's no longer used) or terminating a transfer. + */ +static void pl08x_terminate_phy_chan(struct pl08x_driver_data *pl08x, + struct pl08x_phy_chan *ch) { - u32 val; + u32 val = readl(ch->base + PL080_CH_CONFIG); - pl08x_pause_phy_chan(ch); + val &= ~(PL080_CONFIG_ENABLE | PL080_CONFIG_ERR_IRQ_MASK | + PL080_CONFIG_TC_IRQ_MASK); - /* Disable channel */ - val = readl(ch->base + PL080_CH_CONFIG); - val &= ~PL080_CONFIG_ENABLE; - val &= ~PL080_CONFIG_ERR_IRQ_MASK; - val &= ~PL080_CONFIG_TC_IRQ_MASK; writel(val, ch->base + PL080_CH_CONFIG); + + writel(1 << ch->id, pl08x->base + PL080_ERR_CLEAR); + writel(1 << ch->id, pl08x->base + PL080_TC_CLEAR); } static inline u32 get_bytes_in_cctl(u32 cctl) @@ -404,13 +409,12 @@ static inline void pl08x_put_phy_channel(struct pl08x_driver_data *pl08x, { unsigned long flags; + spin_lock_irqsave(&ch->lock, flags); + /* Stop the channel and clear its interrupts */ - pl08x_stop_phy_chan(ch); - writel((1 << ch->id), pl08x->base + PL080_ERR_CLEAR); - writel((1 << ch->id), pl08x->base + PL080_TC_CLEAR); + pl08x_terminate_phy_chan(pl08x, ch); /* Mark it as free */ - spin_lock_irqsave(&ch->lock, flags); ch->serving = NULL; spin_unlock_irqrestore(&ch->lock, flags); } @@ -1449,7 +1453,7 @@ static int pl08x_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd, plchan->state = PL08X_CHAN_IDLE; if (plchan->phychan) { - pl08x_stop_phy_chan(plchan->phychan); + pl08x_terminate_phy_chan(pl08x, plchan->phychan); /* * Mark physical channel as free and free any slave |