4.18-stable review patch. If anyone has any objections, please let me know.
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From: Yoshihiro Shimoda yoshihiro.shimoda.uh@renesas.com
[ Upstream commit 538603c6026ce769eec633bb79349f5f287519c7 ]
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 Signed-off-by: Sasha Levin alexander.levin@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/dma/sh/rcar-dmac.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
--- a/drivers/dma/sh/rcar-dmac.c +++ b/drivers/dma/sh/rcar-dmac.c @@ -774,8 +774,9 @@ static void rcar_dmac_sync_tcr(struct rc /* 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)