From: Chen Gong <[EMAIL PROTECTED]>
Subject: [PATCH] fix spi_mpc83xx prescale
This updates the SPI clock rate calculations for the spi_mpc83xx
driver. Some boundary conditions were wrong, and in several cases
divide-by-16 wasn't always needed
Signed-off-by: Chen Gong <[EMAIL PROTECTED]>
Signed-off-by: David Brownell <[EMAIL PROTECTED]>
---
drivers/spi/spi_mpc83xx.c | 29 ++++++++++++++++-------------
1 file changed, 16 insertions(+), 13 deletions(-)
--- a/drivers/spi/spi_mpc83xx.c 2008-05-13 15:17:37.000000000 -0700
+++ b/drivers/spi/spi_mpc83xx.c 2008-06-27 18:17:17.000000000 -0700
@@ -266,21 +266,24 @@ int mpc83xx_spi_setup_transfer(struct sp
cs->hw_mode |= SPMODE_LEN(bits_per_word);
- if ((mpc83xx_spi->spibrg / hz) >= 64) {
- pm = mpc83xx_spi->spibrg / (hz * 64) - 1;
- if (pm > 0x0f) {
- dev_err(&spi->dev, "Requested speed is too "
- "low: %d Hz. Will use %d Hz instead.\n",
- hz, mpc83xx_spi->spibrg / 1024);
- pm = 0x0f;
+ if ((mpc83xx_spi->spibrg / hz) > 64) {
+ pm = mpc83xx_spi->spibrg / (hz * 64);
+ if (pm > 16) {
+ cs->hw_mode |= SPMODE_DIV16;
+ pm /= 16;
+ if (pm > 16) {
+ dev_err(&spi->dev, "Requested speed is too "
+ "low: %d Hz. Will use %d Hz instead.\n",
+ hz, mpc83xx_spi->spibrg / 1024);
+ pm = 16;
+ }
}
- cs->hw_mode |= SPMODE_PM(pm) | SPMODE_DIV16;
- } else {
+ } else
pm = mpc83xx_spi->spibrg / (hz * 4);
- if (pm)
- pm--;
- cs->hw_mode |= SPMODE_PM(pm);
- }
+ if (pm)
+ pm--;
+
+ cs->hw_mode |= SPMODE_PM(pm);
regval = mpc83xx_spi_read_reg(&mpc83xx_spi->base->mode);
if (cs->hw_mode != regval) {
unsigned long flags;
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