[PATCH v3] spi: spi-rspi: Fix PIO fallback on RZ platforms

[Biju Das <biju.das.jz@bp.renesas.com>]

RSPI IP on RZ/{A, G2L} SoC's has the same signal for both interrupt
and DMA transfer request. Setting DMARS register for DMA transfer
makes the signal to work as a DMA transfer request signal and
subsequent interrupt requests to the interrupt controller
are masked.

PIO fallback does not work as interrupt signal is disabled.

This patch fixes this issue by re-enabling the interrupts by
calling dmaengine_synchronize().

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
---
v2->v3:
 * dmaengine_synchronize() called unconditionally and removed need_dmar_clr.
v1->v2:
 * Fixed the typo need_dmar_clr->rspi->ops->need_dmar_clr.
---
 drivers/spi/spi-rspi.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/spi/spi-rspi.c b/drivers/spi/spi-rspi.c
index 7a014eeec2d0..411b1307b7fd 100644
--- a/drivers/spi/spi-rspi.c
+++ b/drivers/spi/spi-rspi.c
@@ -613,6 +613,10 @@ static int rspi_dma_transfer(struct rspi_data *rspi, struct sg_table *tx,
 					       rspi->dma_callbacked, HZ);
 	if (ret > 0 && rspi->dma_callbacked) {
 		ret = 0;
+		if (tx)
+			dmaengine_synchronize(rspi->ctlr->dma_tx);
+		if (rx)
+			dmaengine_synchronize(rspi->ctlr->dma_rx);
 	} else {
 		if (!ret) {
 			dev_err(&rspi->ctlr->dev, "DMA timeout\n");
-- 
2.25.1