Off-by-one error, gave erroneous divisor value 16 if speed_hz is over zero but
less than OMAP2_MCSPI_MAX_FREQ / (1 << 15), that is, [1..1463].
Also few overly complex bit shifts in divisor fixed.
Also one dev_dgb line fixed, which indicated max speed exceeding transfer speed.
Introducing a new function omap2_mcspi_calc_divisor() for getting the right
divisor in omap2_mcspi_setup_transfer().
Signed-off-by: Phil Carmody <ext-phil.2.carmody@xxxxxxxxx>
Signed-off-by: Hannu Heikkinen <ext-hannu.m.heikkinen@xxxxxxxxx>
---
drivers/spi/omap2_mcspi.c | 29 ++++++++++++++++++-----------
1 files changed, 18 insertions(+), 11 deletions(-)
diff --git a/drivers/spi/omap2_mcspi.c b/drivers/spi/omap2_mcspi.c
index 36501ad..845248c 100644
--- a/drivers/spi/omap2_mcspi.c
+++ b/drivers/spi/omap2_mcspi.c
@@ -631,6 +631,17 @@ out:
return count - c;
}
+static u32 omap2_mcspi_calc_divisor(u32 speed_hz)
+{
+ u32 div;
+
+ for (div = 0; div < 15; div++)
+ if (speed_hz >= (OMAP2_MCSPI_MAX_FREQ >> div))
+ return div;
+
+ return 15;
+}
+
/* called only when no transfer is active to this device */
static int omap2_mcspi_setup_transfer(struct spi_device *spi,
struct spi_transfer *t)
@@ -653,12 +664,8 @@ static int omap2_mcspi_setup_transfer(struct spi_device *spi,
if (t && t->speed_hz)
speed_hz = t->speed_hz;
- if (speed_hz) {
- while (div <= 15 && (OMAP2_MCSPI_MAX_FREQ / (1 << div))
- > speed_hz)
- div++;
- } else
- div = 15;
+ speed_hz = min(speed_hz, OMAP2_MCSPI_MAX_FREQ);
+ div = omap2_mcspi_calc_divisor(speed_hz);
l = mcspi_cached_chconf0(spi);
@@ -695,7 +702,7 @@ static int omap2_mcspi_setup_transfer(struct spi_device *spi,
mcspi_write_chconf0(spi, l);
dev_dbg(&spi->dev, "setup: speed %d, sample %s edge, clk %s\n",
- OMAP2_MCSPI_MAX_FREQ / (1 << div),
+ OMAP2_MCSPI_MAX_FREQ >> div,
(spi->mode & SPI_CPHA) ? "trailing" : "leading",
(spi->mode & SPI_CPOL) ? "inverted" : "normal");
@@ -996,10 +1003,10 @@ static int omap2_mcspi_transfer(struct spi_device *spi, struct spi_message *m)
t->bits_per_word);
return -EINVAL;
}
- if (t->speed_hz && t->speed_hz < OMAP2_MCSPI_MAX_FREQ/(1<<16)) {
- dev_dbg(&spi->dev, "%d Hz max exceeds %d\n",
- t->speed_hz,
- OMAP2_MCSPI_MAX_FREQ/(1<<16));
+ if (t->speed_hz && t->speed_hz < (OMAP2_MCSPI_MAX_FREQ >> 15)) {
+ dev_dbg(&spi->dev, "speed_hz %d below minimum %d Hz\n",
+ t->speed_hz,
+ OMAP2_MCSPI_MAX_FREQ >> 15);
return -EINVAL;
}
--
1.7.3
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