drivers: spi: rockchip: config spi rx dma burst size depend on xfer length

Change-Id: I54c855fc2ed4ccfbed6c011ae10bebc9829dc4d7
Signed-off-by: Yifeng Zhao <zyf@rock-chips.com>

Author: zhao0116

drivers/spi/spi-rockchip.c

@@ -433,6 +433,19 @@ static void rockchip_spi_dma_txcb(void *data)
 	spin_unlock_irqrestore(&rs->lock, flags);
 }
 
+static u32 rockchip_spi_calc_burst_size(u32 data_len)
+{
+	u32 i;
+
+	/* burst size: 1, 2, 4, 8 */
+	for (i = 1; i < 8; i <<= 1) {
+		if (data_len & i)
+			break;
+	}
+
+	return i;
+}
+
 static int rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 {
 	unsigned long flags;
@@ -452,7 +465,7 @@ static int rockchip_spi_prepare_dma(struct rockchip_spi *rs)
 		rxconf.direction = rs->dma_rx.direction;
 		rxconf.src_addr = rs->dma_rx.addr;
 		rxconf.src_addr_width = rs->n_bytes;
-		rxconf.src_maxburst = 1;
+		rxconf.src_maxburst = rockchip_spi_calc_burst_size(rs->len / rs->n_bytes);
 		dmaengine_slave_config(rs->dma_rx.ch, &rxconf);
 
 		rxdesc = dmaengine_prep_slave_sg(
@@ -585,7 +598,8 @@ static void rockchip_spi_config(struct rockchip_spi *rs)
 	writel_relaxed(rs->fifo_len / 2 - 1, rs->regs + ROCKCHIP_SPI_RXFTLR);
 
 	writel_relaxed(rs->fifo_len / 2 - 1, rs->regs + ROCKCHIP_SPI_DMATDLR);
-	writel_relaxed(0, rs->regs + ROCKCHIP_SPI_DMARDLR);
+	writel_relaxed(rockchip_spi_calc_burst_size(rs->len / rs->n_bytes) - 1,
+		       rs->regs + ROCKCHIP_SPI_DMARDLR);
 	writel_relaxed(dmacr, rs->regs + ROCKCHIP_SPI_DMACR);
 
 	spi_set_clk(rs, div);