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>
/* 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)