From: Jon Smirl <jonsmirl@gmail.com>
To: Timur Tabi <timur@freescale.com>
Cc: linuxppc-dev@ozlabs.org, alsa-devel@alsa-project.org,
broonie@sirena.org.uk
Subject: Re: [alsa-devel] [PATCH] Modify mpc5200 AC97 driver to use V9 of spin_event_timeout()
Date: Tue, 26 May 2009 21:01:00 -0400 [thread overview]
Message-ID: <9e4733910905261801p130f50afie2c50d5723192d44@mail.gmail.com> (raw)
In-Reply-To: <ed82fe3e0905261753v1cb9c901i3b66cd903e4adda6@mail.gmail.com>
On Tue, May 26, 2009 at 8:53 PM, Timur Tabi <timur@freescale.com> wrote:
> On Tue, May 26, 2009 at 7:44 PM, Jon Smirl <jonsmirl@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@gmail.com
next prev parent reply other threads:[~2009-05-27 1:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-27 0:25 [PATCH] Modify mpc5200 AC97 driver to use V9 of spin_event_timeout() Jon Smirl
2009-05-27 0:38 ` [alsa-devel] " Timur Tabi
2009-05-27 0:44 ` Jon Smirl
2009-05-27 0:53 ` Timur Tabi
2009-05-27 1:01 ` Jon Smirl [this message]
2009-05-27 3:12 ` Timur Tabi
2009-05-27 3:49 ` Grant Likely
2009-05-27 3:48 ` Grant Likely
2009-05-27 4:00 ` Grant Likely
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