diff options
| author | Pavel Pisa <ppisa@pikron.com> | 2007-03-07 23:52:40 +0100 |
|---|---|---|
| committer | Russell King <rmk+kernel@arm.linux.org.uk> | 2007-03-12 16:49:34 +0000 |
| commit | 83b84c4e8c7cf00e26610f03ee59e9be010f527c (patch) | |
| tree | 9a7763688a632c8909071b293173800689b7d295 /arch/arm | |
| parent | a45570ebf36c5408ce6cbfd3acd39edf1ada5cda (diff) | |
[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>
Diffstat (limited to 'arch/arm')
| -rw-r--r-- | arch/arm/mach-imx/cpufreq.c | 9 |
1 files changed, 6 insertions, 3 deletions
diff --git a/arch/arm/mach-imx/cpufreq.c b/arch/arm/mach-imx/cpufreq.c index 4f66e90db74..43525ee504d 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) && |