From: Stephen Boyd <sboyd@codeaurora.org>
To: Timur Tabi <timur@tabi.org>
Cc: Arpit Goel <B44344@freescale.com>,
linux@arm.linux.org.uk, takata@linux-m32r.org, philb@gnu.org,
Geert Uytterhoeven <geert@linux-m68k.org>,
schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com,
linux390@de.ibm.com, David Miller <davem@davemloft.net>,
Rob Herring <rob.herring@calxeda.com>,
Arnd Bergmann <arnd@arndb.de>,
Stephen Warren <swarren@nvidia.com>,
john.stultz@linaro.org, jesper.nilsson@axis.com,
gregkh@linuxfoundation.org, sam@ravnborg.org,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>,
lkml <linux-kernel@vger.kernel.org>,
linux-m32r@ml.linux-m32r.org, linux-m32r-ja@ml.linux-m32r.org,
linux-m68k@vger.kernel.org, linux-s390@vger.kernel.org,
sparclinux@vger.kernel.org, mattw@codeaurora.org
Subject: Re: [PATCH 2/2] Convert PowerPC macro spin_event_timeout() to architecture independent macro
Date: Wed, 31 Jul 2013 17:04:14 -0700 [thread overview]
Message-ID: <51F9A5FE.8030608@codeaurora.org> (raw)
In-Reply-To: <CAOZdJXVvNBR-qf7LXNOHZVstH_Rebxwn-wAkSaBS53Wn55mYCw@mail.gmail.com>
On 07/31/13 16:44, Timur Tabi wrote:
> On Wed, Jul 31, 2013 at 2:16 AM, Stephen Boyd <sboyd@codeaurora.org> wrote:
>> What do you do here if jiffies aren't incrementing (i.e
>> interrupts are disabled). The time_before() check won't work
>> there and it would be nice if we were able to use this in such
>> situations. I think powerpc gets around this by reading the
>> hardware timer directly?
> I believe that jiffies is always a global variable. It should behave
> the same on PowerPC as on other architectures.
Yes it's global but it doesn't increment while interrupts are off.
>
> The answer to your question is that you should not use
> spin_event_timeout() in interrupt context, because it yields.
>
If it yields why are we using udelay? Why not usleep_range()? It would
be useful to have a variant that worked in interrupt context and it
looked like that was almost possible.
BTW, couldn't we skip the first patch and just use usecs_to_jiffies()?
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
hosted by The Linux Foundation
next prev parent reply other threads:[~2013-08-01 0:04 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-07-30 12:38 [PATCH 0/2] Make PPC macro spin_event_timeout() architecture independent Arpit Goel
2013-07-30 12:38 ` [PATCH 1/2] Make USECS_PER_JIFFY available for generic use Arpit Goel
2013-07-30 12:38 ` [PATCH 2/2] Convert PowerPC macro spin_event_timeout() to architecture independent macro Arpit Goel
2013-07-31 7:16 ` Stephen Boyd
2013-07-31 23:44 ` Timur Tabi
2013-08-01 0:04 ` Stephen Boyd [this message]
2013-08-01 0:13 ` Timur Tabi
2013-08-01 0:16 ` Stephen Boyd
2013-08-01 0:20 ` Timur Tabi
2013-08-01 1:36 ` Stephen Boyd
2013-08-01 0:02 ` Timur Tabi
2013-07-30 13:08 ` [PATCH 0/2] Make PPC macro spin_event_timeout() architecture independent Geert Uytterhoeven
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