Re: [PATCH] arm: remove unused code in delay.S

[Felipe Contreras]

On Mon, Sep 14, 2009 at 11:10 AM, Russell King - ARM Linux
<linux@xxxxxxxxxxxxxxxx> wrote:
> On Mon, Sep 14, 2009 at 01:21:00AM +0100, Jamie Lokier wrote:
>> Russell King - ARM Linux wrote:
>> > On Sun, Sep 13, 2009 at 11:28:47PM +0200, Marek Vasut wrote:
>> > > >         bhi   __delay
>> > > >         mov   pc, lr
>> > > > ÂENDPROC(__udelay)
>> > > >
>> > > Hi
>> > >
>> > > why was this code there in the first place ?
>> >
>> > To make the delay loop more stable and predictable on older CPUs.
>>
>> So why has it been commented out, if it's needed for that?
>
> We moved on and it penalises later CPUs, leading to udelay providing
> shorter delays than requested.
>
> So the choice was either stable and predictable on older CPUs but
> buggy on newer CPUs, or correct on all CPUs but gives unnecessarily
> longer delays on older CPUs.

Why not add an #ifdef CPU_V4 or whatever?

-- 
Felipe Contreras
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/