From a8d46a7f5d17ca9cbe9e9c7d1d23dc6ea437e141 Mon Sep 17 00:00:00 2001 From: Kuninori Morimoto Date: Fri, 17 Nov 2017 11:00:28 +0900 Subject: dmaengine: rcar-dmac: ensure CHCR DE bit is actually 0 after clearing DMAC reads data from source device, and buffered it until transferable size for sink device. Because of this behavior, DMAC is including buffered data . Now, CHCR DE bit is controlling DMA transfer enable/disable. If DE bit was cleared during data transferring, or during buffering, it will flush buffered data if source device was peripheral device (The buffered data will be removed if source device was memory). Because of this behavior, driver should ensure that DE bit is actually 0 after clearing. This patch adds new rcar_dmac_chcr_de_barrier() and call it after CHCR register access. Signed-off-by: Kuninori Morimoto Tested-by: Hiroyuki Yokoyama Tested-by: Ryo Kodama Tested-by: Geert Uytterhoeven Signed-off-by: Vinod Koul --- drivers/dma/sh/rcar-dmac.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'drivers/dma') diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c index 2b2c7db3e480..c99fd0f6ff13 100644 --- a/drivers/dma/sh/rcar-dmac.c +++ b/drivers/dma/sh/rcar-dmac.c @@ -10,6 +10,7 @@ * published by the Free Software Foundation. */ +#include #include #include #include @@ -741,6 +742,24 @@ static int rcar_dmac_fill_hwdesc(struct rcar_dmac_chan *chan, /* ----------------------------------------------------------------------------- * Stop and reset */ +static void rcar_dmac_chcr_de_barrier(struct rcar_dmac_chan *chan) +{ + u32 chcr; + unsigned int i; + + /* + * Ensure that the setting of the DE bit is actually 0 after + * clearing it. + */ + for (i = 0; i < 1024; i++) { + chcr = rcar_dmac_chan_read(chan, RCAR_DMACHCR); + if (!(chcr & RCAR_DMACHCR_DE)) + return; + udelay(1); + } + + dev_err(chan->chan.device->dev, "CHCR DE check error\n"); +} static void rcar_dmac_chan_halt(struct rcar_dmac_chan *chan) { @@ -749,6 +768,7 @@ static void rcar_dmac_chan_halt(struct rcar_dmac_chan *chan) chcr &= ~(RCAR_DMACHCR_DSE | RCAR_DMACHCR_DSIE | RCAR_DMACHCR_IE | RCAR_DMACHCR_TE | RCAR_DMACHCR_DE); rcar_dmac_chan_write(chan, RCAR_DMACHCR, chcr); + rcar_dmac_chcr_de_barrier(chan); } static void rcar_dmac_chan_reinit(struct rcar_dmac_chan *chan) @@ -1481,6 +1501,8 @@ static irqreturn_t rcar_dmac_isr_channel(int irq, void *dev) if (chcr & RCAR_DMACHCR_TE) mask |= RCAR_DMACHCR_DE; rcar_dmac_chan_write(chan, RCAR_DMACHCR, chcr & ~mask); + if (mask & RCAR_DMACHCR_DE) + rcar_dmac_chcr_de_barrier(chan); if (chcr & RCAR_DMACHCR_DSE) ret |= rcar_dmac_isr_desc_stage_end(chan); -- cgit v1.2.3