[PATCH 4.14 027/189] spi: cadence: Add usleep_range() for cdns_spi_fill_tx_fifo()

Greg Kroah-Hartman
2018-06-18T08:31:26Z

From: sxauwsk <sxauwsk@163.com>

[ Upstream commit 49530e6411789c1b9ea3ebc58e520c19d1c3752f ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/spi/spi-cadence.c | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/drivers/spi/spi-cadence.c
+++ b/drivers/spi/spi-cadence.c
@@ -313,6 +313,14 @@ static void cdns_spi_fill_tx_fifo(struct

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