From: Muhammad Hamza Farooq <mfarooq@xxxxxxxxxxx> DMA engine does not stop instantaneously when transaction is going on (see datasheet). Wait has been added Signed-off-by: Muhammad Hamza Farooq <mfarooq@xxxxxxxxxxx> --- drivers/dma/sh/rcar-dmac.c | 29 ++++++++++++++++++++++++++--- 1 file changed, 26 insertions(+), 3 deletions(-) diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c index 7820d07..920f977 100644 --- a/drivers/dma/sh/rcar-dmac.c +++ b/drivers/dma/sh/rcar-dmac.c @@ -716,14 +716,37 @@ static int rcar_dmac_fill_hwdesc(struct rcar_dmac_chan *chan, /* ----------------------------------------------------------------------------- * Stop and reset */ +#define NR_READS_TO_WAIT (5) /* number of reads to perform to check DE = 0 */ +static inline int rcar_dmac_wait_stop(struct rcar_dmac_chan *chan) +{ + unsigned int i = 0; + do { + u32 chcr = rcar_dmac_chan_read(chan, RCAR_DMACHCR); + + if(!(chcr & RCAR_DMACHCR_DE)) + return 0; + dev_dbg(chan->chan.device->dev, "DMA transfer couldn't be stopped"); + } + while(++i < NR_READS_TO_WAIT); -static void rcar_dmac_chan_halt(struct rcar_dmac_chan *chan) + return -EBUSY; +} + +/* Called with chan lock held */ +static int rcar_dmac_chan_halt(struct rcar_dmac_chan *chan) { - u32 chcr = rcar_dmac_chan_read(chan, RCAR_DMACHCR); + u32 chcr; + int ret; + chcr = rcar_dmac_chan_read(chan, RCAR_DMACHCR); chcr &= ~(RCAR_DMACHCR_DSE | RCAR_DMACHCR_DSIE | RCAR_DMACHCR_IE | - RCAR_DMACHCR_TE | RCAR_DMACHCR_DE); + RCAR_DMACHCR_TE | RCAR_DMACHCR_DE); rcar_dmac_chan_write(chan, RCAR_DMACHCR, chcr); + ret = rcar_dmac_wait_stop(chan); + + WARN_ON(ret < 0); + + return ret; } static void rcar_dmac_chan_reinit(struct rcar_dmac_chan *chan) -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html