spi: cadence: Add usleep_range() for cdns_spi_fill_tx_fifo()

In case of xspi work in busy condition, may send bytes failed.
once something wrong, spi controller did't work any more

My test found this situation appear in both of read/write process.
so when TX FIFO is full, add one byte delay before send data;

Signed-off-by: sxauwsk <sxauwsk@163.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/spi/spi-cadence.c b/drivers/spi/spi-cadence.c
index 5c9516ae4942..4a001634023e 100644
--- a/drivers/spi/spi-cadence.c
+++ b/drivers/spi/spi-cadence.c
@@ -313,6 +313,14 @@ static void cdns_spi_fill_tx_fifo(struct cdns_spi *xspi)
 
         while ((trans_cnt < CDNS_SPI_FIFO_DEPTH) &&
                (xspi->tx_bytes > 0)) {
+
+                /* When xspi in busy condition, bytes may send failed,
+                 * then spi control did't work thoroughly, add one byte delay
+                 */
+                if (cdns_spi_read(xspi, CDNS_SPI_ISR) &
+                    CDNS_SPI_IXR_TXFULL)
+                        usleep_range(10, 20);
+
                 if (xspi->txbuf)
                         cdns_spi_write(xspi, CDNS_SPI_TXD, *xspi->txbuf++);
                 else