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spi: lpspi: add the error info of transfer speed setting 

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>
Signed-off-by: Mark Brown <broonie@kernel.org>
This commit is contained in:
Clark Wang 2019-03-06 06:30:41 +00:00 committed by Mark Brown
parent 944c01a889
commit 77736a98b8
No known key found for this signature in database
GPG Key ID: 24D68B725D5487D0
1 changed files with 13 additions and 3 deletions
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16
drivers/spi/spi-fsl-lpspi.c
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@ -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;