Duration of mdelay and udelay depends on MPU frequency in SMP

Menon, Nishanth nm at ti.com
Fri Jun 10 18:19:13 EDT 2011

On Thu, May 12, 2011 at 01:42, Santosh Shilimkar
<santosh.shilimkar at ti.com> wrote:
> On 5/5/2011 12:23 PM, Saquib wrote:
>> Can anyone please help me to understand and fix this issue?
>> When CPU frequency is "1008MHz", duration of delay was close to
>> theoretical value, however, when "300MHz", it was close to about 4 times
>> the theoretical value.
>> I tested it on OMAP4(SMP) blaze board.
> It's a well known problem if the udelay() is based of global lpj.
> You can read more here [1]
> Regards
> Santosh
> [1] http://eeek.borgchat.net/lists/arm-kernel/msg120702.html
I am curious about this topic now.
Searching Russel's patchworks for this:
I see nothing queued. What is the recommendation for udelay?

Nishanth Menon

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