spi/rockchip: Avoid accidentally turning off the clock

If our client is requesting a clock that is above the maximum clock
then the following division will result in 0:
  rs->max_freq / rs->speed

We'll then program 0 into the SPI_BAUDR register.  The Rockchip TRM
says: "If the value is 0, the serial output clock (sclk_out) is
disabled."

It's much better to end up with the fastest possible clock rather than
a clock that is off, so enforce a minimum value.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/drivers/spi/spi-rockchip.c b/drivers/spi/spi-rockchip.c
index 6321326..cd0e08b 100644 (file)
--- a/drivers/spi/spi-rockchip.c
+++ b/drivers/spi/spi-rockchip.c
@@ -499,7 +499,7 @@ static void rockchip_spi_config(struct rockchip_spi *rs)
        }
 
        /* div doesn't support odd number */
-       div = rs->max_freq / rs->speed;
+       div = max_t(u32, rs->max_freq / rs->speed, 1);
        div = (div + 1) & 0xfffe;
 
        spi_enable_chip(rs, 0);