From 83b84c4e8c7cf00e26610f03ee59e9be010f527c Mon Sep 17 00:00:00 2001
From: Pavel Pisa <ppisa@pikron.com>
Date: Wed, 7 Mar 2007 23:52:40 +0100
Subject: [ARM] 4254/1: i.MX/MX1 CPU Frequency scaling honor boot loader set
BCLK_DIV.
The minimal bus clock prescaler should be kept at value
selected by the board / boot loader designer.
Switching frequency above startup limit could
lead to the external memory/devices misbehave.
Signed-off-by: Pavel Pisa <pisa@cmp.felk.cvut.cz>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---
arch/arm/mach-imx/cpufreq.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
(limited to 'arch/arm/mach-imx/cpufreq.c')
diff --git a/arch/arm/mach-imx/cpufreq.c b/arch/arm/mach-imx/cpufreq.c
index 4f66e90db74f..43525ee504d5 100644
--- a/arch/arm/mach-imx/cpufreq.c
+++ b/arch/arm/mach-imx/cpufreq.c
@@ -50,6 +50,7 @@
#define CR_920T_ASYNC_MODE 0xC0000000
static u32 mpctl0_at_boot;
+static u32 bclk_div_at_boot;
static void imx_set_async_mode(void)
{
@@ -182,7 +183,7 @@ static int imx_set_target(struct cpufreq_policy *policy,
unsigned long flags;
long freq;
long sysclk;
- unsigned int bclk_div = 1;
+ unsigned int bclk_div = bclk_div_at_boot;
/*
* Some governors do not respects CPU and policy lower limits
@@ -202,7 +203,7 @@ static int imx_set_target(struct cpufreq_policy *policy,
sysclk = imx_get_system_clk();
- if (freq > sysclk + 1000000) {
+ if (freq > sysclk / bclk_div_at_boot + 1000000) {
freq = imx_compute_mpctl(&mpctl0, mpctl0_at_boot, freq, relation);
if (freq < 0) {
printk(KERN_WARNING "imx: target frequency %ld Hz cannot be set\n", freq);
@@ -217,6 +218,8 @@ static int imx_set_target(struct cpufreq_policy *policy,
if(bclk_div > 16)
bclk_div = 16;
+ if(bclk_div < bclk_div_at_boot)
+ bclk_div = bclk_div_at_boot;
}
freq = (sysclk + bclk_div / 2) / bclk_div;
}
@@ -285,7 +288,7 @@ static struct cpufreq_driver imx_driver = {
static int __init imx_cpufreq_init(void)
{
-
+ bclk_div_at_boot = __mfld2val(CSCR_BCLK_DIV, CSCR) + 1;
mpctl0_at_boot = 0;
if((CSCR & CSCR_MPEN) &&
--
cgit v1.2.3