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| author | Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com> | 2018-07-02 18:18:03 +0900 |
|---|---|---|
| committer | Vinod Koul <vkoul@kernel.org> | 2018-07-10 20:49:46 +0530 |
| commit | 538603c6026ce769eec633bb79349f5f287519c7 (patch) | |
| tree | fb908a88e463a1890f9fb4e410c5d04bf7d87b49 /drivers/dma | |
| parent | e919417bd6468b7f1b2899200a78f1ad078757d3 (diff) | |
| download | linux-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.c | 5 |
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) |