Commit fb526210 authored by Russell King - ARM Linux's avatar Russell King - ARM Linux Committed by Dan Williams
Browse files

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: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
Acked-by: default avatarLinus Walleij <linus.walleij@stericsson.com>
Signed-off-by: default avatarDan Williams <dan.j.williams@intel.com>
parent d718f4eb

drivers/dma/amba-pl08x.c

+18 −14
Original line number Diff line number Diff line
@@ -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

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