[PATCH] spi: lpspi: fix dataloss when SS is inactivated between every words

From: Clark Wang
Date: Thu Mar 21 2019 - 05:57:12 EST

If we don't use CONT to keep SS activated or use DMA mode without
cs-gpio, SS will be inactivated between every words. The word here
means the data sent once which length can be set as 1/2/4 bytes.

In the isr function, we read the FSR_RXCOUNT just behind the
fsl_lpspi_read_rx_fifo. This causes the value of FSR_RXCOUNT cannot
reflect whether there is still data not sent timely. So do this
judgement by FSR_TXCOUNT.

Signed-off-by: Clark Wang <xiaoning.wang@xxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
drivers/spi/spi-fsl-lpspi.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c
index 391863914043..9e117c4635d8 100644
--- a/drivers/spi/spi-fsl-lpspi.c
+++ b/drivers/spi/spi-fsl-lpspi.c
@@ -62,7 +62,7 @@
#define CFGR1_PCSPOL BIT(8)
#define CFGR1_NOSTALL BIT(3)
#define CFGR1_MASTER BIT(0)
-#define FSR_RXCOUNT (BIT(16)|BIT(17)|BIT(18))
+#define FSR_TXCOUNT (0xFF)
#define RSR_RXEMPTY BIT(1)
#define TCR_CPOL BIT(31)
#define TCR_CPHA BIT(30)
@@ -452,7 +452,7 @@ static irqreturn_t fsl_lpspi_isr(int irq, void *dev_id)

if (temp_SR & SR_MBF ||
- readl(fsl_lpspi->base + IMX7ULP_FSR) & FSR_RXCOUNT) {
+ readl(fsl_lpspi->base + IMX7ULP_FSR) & FSR_TXCOUNT) {
writel(SR_FCF, fsl_lpspi->base + IMX7ULP_SR);
fsl_lpspi_intctrl(fsl_lpspi, IER_FCIE);