[U-Boot] [PATCH] arm925t: Fix CONFIG_SYS_HZ to 1000

[Ladislav Michl <ladis@linux-mips.org>]

On Tue, Apr 21, 2009 at 05:38:21PM +0200, Dirk Behme wrote:
> Ladislav Michl wrote:
>> On Mon, Apr 20, 2009 at 08:27:34PM +0200, Dirk Behme wrote:
>>> Just to get an idea of the math:
>>>
>>> CONFIG_SYS_CLK_FREQ is 12000000 (12MHz)? This is divided by 256, so   
>>> TIMER_CLOCK is 46875Hz? A free running 32-bit count down timer is 
>>> used  starting at 0xffffffff? Underflow (0) is reached after ~91626s 
>>> ==  ~25hours with this?
>>>
>>> Please correct if something is wrong ;)
>>
>> Math is perfectly correct, except in my case CONFIG_SYS_CLK_FREQ is 150MHz,
>> so resolution is actually 12.5 times better. 
>
> Ok. Is this 150MHz defined in one of the configs you modify with this  
> patch or do you use a custom config? Just curious ;)

All three 32-bit counters receive a dedicated clock from clock generator
module 1 (either CLKIN or DPLL1 output). You will find CONFIG_SYS_CLK_FREQ
defined to be 150000000 in include/configs/netstar.h and code in
board/netstar/setup.S selects DPLL1 as a clock source (and you'll probably
notice that netstar's lowlevel_init code looks different from all others just
because it was not copied, but written from scratch long before its author
even explored u-boot's existence, so take care when copying anything from
netstar's config file as it handles low level init different way).

>> Perhaps I should modify those
>> boards wich uses 12MHz clock to use smaller divisor, 
>
> Yes, this should be easily doable by changing CONFIG_SYS_PTV.

Yes, I'll send updated patch.

[snip]
>> Right, but the key point here is to unbind udelay from get_timer as now
>> get_timer works with miliseconds resolution.
>
> I hope I got it right with the updated patch sent some minutes ago.

Yes, that one looks definitely better (although I have no way to test it).

	ladis