Re: [PATCHv4 0/4] ARM: Fixing udelay() for SMP and non-SMP systems

[Saravana Kannan]

On 03/04/2011 02:10 AM, Linus Walleij wrote:
> 2010/12/20 Stephen Boyd<sboyd@xxxxxxxxxxxxxx>:
>
> > These patches fix the udelay() issue pointed out on
> > arm-lkml[1][2]. A quick recap: some SMP machines can scale
> > their CPU frequencies independent of one another. loops_per_jiffy
> > is calibrated globally and used in __const_udelay(). If one CPU
> > is running faster than what the loops_per_jiffy is calculated
> > (or scaled) for, udelay() will be incorrect and not wait long
> > enough (or too long). A similar problem occurs if the cpu
> > frequency is scaled during a udelay() call.
>
> Hwt's happening to this patch set? We have applied it and
> implemented a timer for the U8500.
>
> Tested-by: Linus Walleij<linus.walleij@xxxxxxxxxx>
>
> Mattias WALLIN can probably also provide a Tested-by:
> from ST-Ericsson if it helps.
>
> Generally I think this is good and important stuff that should
> be merged, will you be submitting it to Russells patch tracker
> or pull request for 2.6.39?

Thanks for testing and reporting it Linus. We are certainly interested 
in getting this in. If I'm not mistaken, the last time we sent it out, 
there was a C vs. assembly argument and got side tracked or no one acked 
or responded to it. Will try to send out the patches again within the 
next few weeks.

Thanks,
Saravana

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