diff options
Diffstat (limited to 'drivers/dma')
| -rw-r--r-- | drivers/dma/amba-pl08x.c | 21 |
1 files changed, 15 insertions, 6 deletions
diff --git a/drivers/dma/amba-pl08x.c b/drivers/dma/amba-pl08x.c index 8321a3997c9..07bca4970e5 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) |