1 files changed, 9 insertions, 3 deletions

diff --git a/drivers/spi/davinci_spi.c b/drivers/spi/davinci_spi.c
index 95afb6b77395..b85090caf7cf 100644
--- a/drivers/spi/davinci_spi.c
+++ b/drivers/spi/davinci_spi.c
@@ -301,7 +301,7 @@ static int davinci_spi_setup_transfer(struct spi_device *spi,
         struct davinci_spi *davinci_spi;
         struct davinci_spi_platform_data *pdata;
         u8 bits_per_word = 0;
-        u32 hz = 0, prescale;
+        u32 hz = 0, prescale = 0, clkspeed;
 
         davinci_spi = spi_master_get_devdata(spi->master);
         pdata = davinci_spi->pdata;
@@ -338,10 +338,16 @@ static int davinci_spi_setup_transfer(struct spi_device *spi,
         set_fmt_bits(davinci_spi->base, bits_per_word & 0x1f,
                         spi->chip_select);
 
-        prescale = ((clk_get_rate(davinci_spi->clk) / hz) - 1) & 0xff;
+        clkspeed = clk_get_rate(davinci_spi->clk);
+        if (hz > clkspeed / 2)
+                prescale = 1 << 8;
+        if (hz < clkspeed / 256)
+                prescale = 255 << 8;
+        if (!prescale)
+                prescale = ((clkspeed / hz - 1) << 8) & 0x0000ff00;
 
         clear_fmt_bits(davinci_spi->base, 0x0000ff00, spi->chip_select);
-        set_fmt_bits(davinci_spi->base, prescale << 8, spi->chip_select);
+        set_fmt_bits(davinci_spi->base, prescale, spi->chip_select);
 
         return 0;
 }