spi: bcm2835: clock divider can be a multiple of 2

The official documentation is wrong in this respect.
Has been tested empirically for dividers 2-1024

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 960dcce607c2..8de1925fe554 100644
--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -153,8 +153,9 @@ static int bcm2835_spi_start_transfer(struct spi_device *spi,
         if (spi_hz >= clk_hz / 2) {
                 cdiv = 2; /* clk_hz/2 is the fastest we can go */
         } else if (spi_hz) {
-                /* CDIV must be a power of two */
-                cdiv = roundup_pow_of_two(DIV_ROUND_UP(clk_hz, spi_hz));
+                /* CDIV must be a multiple of two */
+                cdiv = DIV_ROUND_UP(clk_hz, spi_hz);
+                cdiv += (cdiv % 2);
 
                 if (cdiv >= 65536)
                         cdiv = 0; /* 0 is the slowest we can go */