[PATCH 4/7] spi: dw: Force set K210 fifo length to 31

[Niklas Cassel]

From: Damien Le Moal <damien.lemoal at opensource.wdc.com>

The Canaan Kendryte K210 SoC DW apb_ssi v4 spi controller is documented
to have a 32 word deep TX and RX FIFO, which spi_hw_init() detects.
However, when the RX FIFO is filled up to 32 entries (RXFLR = 32), an
RX FIFO overrun error occurs. Avoid this problem by force setting
fifo_len to 31.

Signed-off-by: Damien Le Moal <damien.lemoal at opensource.wdc.com>
Signed-off-by: Niklas Cassel <niklas.cassel at wdc.com>
---
 drivers/spi/designware_spi.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/designware_spi.c b/drivers/spi/designware_spi.c
index 9200efced9..f9b19a5ea4 100644
--- a/drivers/spi/designware_spi.c
+++ b/drivers/spi/designware_spi.c
@@ -194,6 +194,20 @@ static int dw_spi_apb_init(struct udevice *bus, struct dw_spi_priv *priv)
 	return 0;
 }
 
+static int dw_spi_apb_k210_init(struct udevice *bus, struct dw_spi_priv *priv)
+{
+	/*
+	 * The Canaan Kendryte K210 SoC DW apb_ssi v4 spi controller is
+	 * documented to have a 32 word deep TX and RX FIFO, which
+	 * spi_hw_init() detects. However, when the RX FIFO is filled up to
+	 * 32 entries (RXFLR = 32), an RX FIFO overrun error occurs. Avoid
+	 * this problem by force setting fifo_len to 31.
+	 */
+	priv->fifo_len = 31;
+
+	return dw_spi_apb_init(bus, priv);
+}
+
 static int dw_spi_dwc_init(struct udevice *bus, struct dw_spi_priv *priv)
 {
 	priv->max_xfer = 32;
@@ -758,7 +772,7 @@ static const struct udevice_id dw_spi_ids[] = {
 	 */
 	{ .compatible = "altr,socfpga-spi", .data = (ulong)dw_spi_apb_init },
 	{ .compatible = "altr,socfpga-arria10-spi", .data = (ulong)dw_spi_apb_init },
-	{ .compatible = "canaan,k210-spi", .data = (ulong)dw_spi_apb_init },
+	{ .compatible = "canaan,k210-spi", .data = (ulong)dw_spi_apb_k210_init},
 	{ .compatible = "canaan,k210-ssi", .data = (ulong)dw_spi_dwc_init },
 	{ .compatible = "intel,stratix10-spi", .data = (ulong)dw_spi_apb_init },
 	{ .compatible = "intel,agilex-spi", .data = (ulong)dw_spi_apb_init },
-- 
2.35.1