diff options
Diffstat (limited to 'drivers/dma/amba-pl08x.c')
| -rw-r--r-- | drivers/dma/amba-pl08x.c | 53 |
1 files changed, 33 insertions, 20 deletions
diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c index 297f48b..07bca49 100644 --- a/drivers/dma/amba-pl08x.c +++ b/drivers/dma/amba-pl08x.c @@ -79,6 +79,7 @@ #include <linux/module.h> #include <linux/interrupt.h> #include <linux/slab.h> +#include <linux/delay.h> #include <linux/dmapool.h> #include <linux/dmaengine.h> #include <linux/amba/bus.h> @@ -235,16 +236,19 @@ static void pl08x_start_txd(struct pl08x_dma_chan *plchan, } /* - * Overall DMAC remains enabled always. + * Pause the channel by setting the HALT bit. * - * Disabling individual channels could lose data. + * For M->P transfers, pause the DMAC first and then stop the peripheral - + * the FIFO can only drain if the peripheral is still requesting data. + * (note: this can still timeout if the DMAC FIFO never drains of data.) * - * Disable the peripheral DMA after disabling the DMAC in order to allow - * the DMAC FIFO to drain, and hence allow the channel to show inactive + * For P->M transfers, disable the peripheral first to stop it filling + * the DMAC FIFO, and then pause the DMAC. */ static void pl08x_pause_phy_chan(struct pl08x_phy_chan *ch) { u32 val; + int timeout; /* Set the HALT bit and wait for the FIFO to drain */ val = readl(ch->base + PL080_CH_CONFIG); @@ -252,8 +256,13 @@ static void pl08x_pause_phy_chan(struct pl08x_phy_chan *ch) writel(val, ch->base + PL080_CH_CONFIG); /* Wait for channel inactive */ - while (pl08x_phy_channel_busy(ch)) - cpu_relax(); + for (timeout = 1000; timeout; timeout--) { + if (!pl08x_phy_channel_busy(ch)) + break; + udelay(1); + } + if (pl08x_phy_channel_busy(ch)) + pr_err("pl08x: channel%u timeout waiting for pause\n", ch->id); } static void pl08x_resume_phy_chan(struct pl08x_phy_chan *ch) @@ -267,19 +276,24 @@ 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 +418,12 @@ 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 +1462,7 @@ 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 |
