From 210b49231af6a3ede5de3c90850dbf1134a855c2 Mon Sep 17 00:00:00 2001
From: Martin Sperl <kernel@martin.sperl.org>
Date: Thu, 19 Mar 2015 09:01:52 +0000
Subject: [PATCH] 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>
---
drivers/spi/spi-bcm2835.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c
index 960dcce607c2c..8de1925fe5548 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 */