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Subject[PATCH V2 4/8] spi: lpspi: add the error info of transfer speed setting
Date
Add a error info when set a speed which greater than half of per-clk of
spi module.

The minimum SCK period is 2 cycles(CCR[SCKDIV]). So the maximum transfer
speed is half of spi per-clk.

Signed-off-by: Clark Wang <xiaoning.wang@nxp.com>
---
V2:
- No change. Resend for applying.
---
drivers/spi/spi-fsl-lpspi.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/spi/spi-fsl-lpspi.c b/drivers/spi/spi-fsl-lpspi.c
index 84dcb9e176b8..69635cde0e22 100644
--- a/drivers/spi/spi-fsl-lpspi.c
+++ b/drivers/spi/spi-fsl-lpspi.c
@@ -255,6 +255,13 @@ static int fsl_lpspi_set_bitrate(struct fsl_lpspi_data *fsl_lpspi)
u8 prescale;

perclk_rate = clk_get_rate(fsl_lpspi->clk_per);
+
+ if (config.speed_hz > perclk_rate / 2) {
+ dev_err(fsl_lpspi->dev,
+ "per-clk should be at least two times of transfer speed");
+ return -EINVAL;
+ }
+
for (prescale = 0; prescale < 8; prescale++) {
scldiv = perclk_rate /
(clkdivs[prescale] * config.speed_hz) - 2;
@@ -304,7 +311,7 @@ static int fsl_lpspi_config(struct fsl_lpspi_data *fsl_lpspi)
return 0;
}

-static void fsl_lpspi_setup_transfer(struct spi_device *spi,
+static int fsl_lpspi_setup_transfer(struct spi_device *spi,
struct spi_transfer *t)
{
struct fsl_lpspi_data *fsl_lpspi =
@@ -337,7 +344,7 @@ static void fsl_lpspi_setup_transfer(struct spi_device *spi,
else
fsl_lpspi->watermark = fsl_lpspi->txfifosize;

- fsl_lpspi_config(fsl_lpspi);
+ return fsl_lpspi_config(fsl_lpspi);
}

static int fsl_lpspi_slave_abort(struct spi_controller *controller)
@@ -429,7 +436,10 @@ static int fsl_lpspi_transfer_one_msg(struct spi_controller *controller,
msg->actual_length = 0;

list_for_each_entry(xfer, &msg->transfers, transfer_list) {
- fsl_lpspi_setup_transfer(spi, xfer);
+ ret = fsl_lpspi_setup_transfer(spi, xfer);
+ if (ret < 0)
+ goto complete;
+
fsl_lpspi_set_cmd(fsl_lpspi, is_first_xfer);

is_first_xfer = false;
--
2.17.1
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