spi: dw: Enable interrupts in accordance with DMA xfer mode

It's pointless to track the Tx overrun interrupts if Rx-only SPI
transfer is issued. Similarly there is no need in handling the Rx
overrun/underrun interrupts if Tx-only SPI transfer is executed.
So lets unmask the interrupts only if corresponding SPI
transactions are implied.

Co-developed-by: Georgy Vlasov <[email protected]>
Signed-off-by: Georgy Vlasov <[email protected]>
Signed-off-by: Serge Semin <[email protected]>
Cc: Ramil Zaripov <[email protected]>
Cc: Alexey Malahov <[email protected]>
Cc: Thomas Bogendoerfer <[email protected]>
Cc: Paul Burton <[email protected]>
Cc: Ralf Baechle <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Andy Shevchenko <[email protected]>
Cc: Rob Herring <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mark Brown <[email protected]>

Author: fancer

drivers/spi/spi-dw-mid.c

@@ -243,19 +243,23 @@ static struct dma_async_tx_descriptor *dw_spi_dma_prepare_rx(struct dw_spi *dws,
 
 static int mid_spi_dma_setup(struct dw_spi *dws, struct spi_transfer *xfer)
 {
-	u16 dma_ctrl = 0;
+	u16 imr = 0, dma_ctrl = 0;
 
 	dw_writel(dws, DW_SPI_DMARDLR, 0xf);
 	dw_writel(dws, DW_SPI_DMATDLR, 0x10);
 
-	if (xfer->tx_buf)
+	if (xfer->tx_buf) {
 		dma_ctrl |= SPI_DMA_TDMAE;
-	if (xfer->rx_buf)
+		imr |= SPI_INT_TXOI;
+	}
+	if (xfer->rx_buf) {
 		dma_ctrl |= SPI_DMA_RDMAE;
+		imr |= SPI_INT_RXUI | SPI_INT_RXOI;
+	}
 	dw_writel(dws, DW_SPI_DMACR, dma_ctrl);
 
 	/* Set the interrupt mask */
-	spi_umask_intr(dws, SPI_INT_TXOI | SPI_INT_RXUI | SPI_INT_RXOI);
+	spi_umask_intr(dws, imr);
 
 	dws->transfer_handler = dma_transfer;