[alsa-devel] [PATCH] Modify mpc5200 AC97 driver to use V9 of spin_event_timeout()

Jon Smirl jonsmirl at gmail.com
Wed May 27 03:01:00 CEST 2009

On Tue, May 26, 2009 at 8:53 PM, Timur Tabi <timur at freescale.com> wrote:
> On Tue, May 26, 2009 at 7:44 PM, Jon Smirl <jonsmirl at gmail.com> wrote:
>> Because Grant didn't want me doing udelay(50) just to delay things in
>> order to give the AC97 controller time to initialize. Your function
>> lets me loop on cpu_relax() for 50us.
> But udelay() calls HMT_low(), which is like cpu_relax().

Then why did you need to make your routine that calls cpu_relax()?

I don't know what goes on in the guts of HMT_low() and cpu_relax(),
when you guys decide which one I should use let me know and I can
adjust the patch.

The hardware needs a minimum 50us pause. It doesn't matter if the
pause is more than that. If the CPU has something to keep it busy for
a few milliseconds that's fine.

> --
> Timur Tabi
> Linux kernel developer at Freescale

Jon Smirl
jonsmirl at gmail.com

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