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authorYoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>2018-07-02 18:18:03 +0900
committerVinod Koul <vkoul@kernel.org>2018-07-10 20:49:46 +0530
commit538603c6026ce769eec633bb79349f5f287519c7 (patch)
treefb908a88e463a1890f9fb4e410c5d04bf7d87b49 /drivers/dma
parente919417bd6468b7f1b2899200a78f1ad078757d3 (diff)
downloadlinux-538603c6026ce769eec633bb79349f5f287519c7.tar.bz2
dmaengine: sh: rcar-dmac: avoid to write CHCR.TE to 1 if TCR is set to 0
This patch fixes an issue that unexpected retransfering happens if TCR is set to 0 before rcar_dmac_sync_tcr() writes DE bit to the CHCR register. For example, sh-sci driver can reproduce this issue like below: In rx_timer_fn(): /* CHCR DE bit may be set to 1 */ dmaengine_tx_status() rcar_dmac_tx_status() rcar_dmac_chan_get_residue() rcar_dmac_sync_tcr() /* TCR is possible to be set to 0 */ According to the description of commit 73a47bd0da66 ("dmaengine: rcar-dmac: use TCRB instead of TCR for residue"), "this buffered data will be transferred if CHCR::DE bit was cleared". So, this patch doesn't need to check TCRB register. Fixes: 73a47bd0da66 ("dmaengine: rcar-dmac: use TCRB instead of TCR for residue") Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> Signed-off-by: Vinod Koul <vkoul@kernel.org>
Diffstat (limited to 'drivers/dma')
-rw-r--r--drivers/dma/sh/rcar-dmac.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/drivers/dma/sh/rcar-dmac.c b/drivers/dma/sh/rcar-dmac.c
index 9dc73ac92359..9906a9c7220b 100644
--- a/drivers/dma/sh/rcar-dmac.c
+++ b/drivers/dma/sh/rcar-dmac.c
@@ -772,8 +772,9 @@ static void rcar_dmac_sync_tcr(struct rcar_dmac_chan *chan)
/* make sure all remaining data was flushed */
rcar_dmac_chcr_de_barrier(chan);
- /* back DE */
- rcar_dmac_chan_write(chan, RCAR_DMACHCR, chcr);
+ /* back DE if remain data exists */
+ if (rcar_dmac_chan_read(chan, RCAR_DMATCR))
+ rcar_dmac_chan_write(chan, RCAR_DMACHCR, chcr);
}
static void rcar_dmac_chan_halt(struct rcar_dmac_chan *chan)