[U-Boot] [PATCH v2] spi: zynq_spi: Fix infinite looping while xfer

[Lad Prabhakar]

From: "Lad, Prabhakar" <prabhakar.csengg at gmail.com>

During spi transfer, for example:
sspi 1:1.0 8 ff

the rx_len values will  be:
rx_len = 0
rx_len = 4294967295

This caused a busy looping during xfer, this patch fixes it
by adding a check while reading the rx fifo

Signed-off-by: Lad, Prabhakar <prabhakar.csengg at gmail.com>
Cc: Michal Simek <michal.simek at xilinx.com>
Cc: Siva Durga Prasad Paladugu <sivadur at xilinx.com>
Cc: Jagan Teki <jteki at openedev.com>
---
 Changes for v2: None
 
 drivers/spi/zynq_spi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/spi/zynq_spi.c b/drivers/spi/zynq_spi.c
index 09ae1be..dd3de27 100644
--- a/drivers/spi/zynq_spi.c
+++ b/drivers/spi/zynq_spi.c
@@ -230,7 +230,7 @@ static int zynq_spi_xfer(struct udevice *dev, unsigned int bitlen,
 
 		/* Read the data from RX FIFO */
 		status = readl(&regs->isr);
-		while (status & ZYNQ_SPI_IXR_RXNEMPTY_MASK) {
+		while ((status & ZYNQ_SPI_IXR_RXNEMPTY_MASK) && rx_len) {
 			buf = readl(&regs->rxdr);
 			if (rx_buf)
 				*rx_buf++ = buf;
-- 
1.9.1