Re: mdelay() from board_setup() [is default value for loops_per_jiffy way off?]

[Pete Popov <ppopov@embeddedalley.com>]

Clem Taylor wrote:
> Hi,
>
> I'm working on a linux port for a custom Au1550 based board. Inside of
> board_setup() I need to wait for some hardware to power up. So, I
> called mdelay(), but it seems to wait for far too short a time. It
> seems that loops_per_jiffy still has the default value (4096) in
> board_setup(), the computed value is more like 245248. So, what is the
> proper way to spin wait this early in the startup process? Also, isn't
> the default value for loops_per_jiffy off by quite a bit? I'm running
> the Au1550 at 492MHz, so that would make the default value good for a
> ~8MHz processor?
It's too early in board_setup() to use the standard delay routines. You can't 
use those until after calibrate_delay() runs. To do precise delays in 
board_setup, you'll have to do something yourself where you read the cp0 timer 
periodically and wait a certain amount of time.
Pete