From: felipe.contreras@gmail.com (Felipe Contreras)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] arm: remove unused code in delay.S
Date: Mon, 14 Sep 2009 15:58:24 +0300 [thread overview]
Message-ID: <94a0d4530909140558nd8d2c47lc9954563c80a574f@mail.gmail.com> (raw)
In-Reply-To: <20090914081001.GB14519@n2100.arm.linux.org.uk>
On Mon, Sep 14, 2009 at 11:10 AM, Russell King - ARM Linux
<linux@arm.linux.org.uk> 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
>> > > > ?ENDPROC(__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
next prev parent reply other threads:[~2009-09-14 12:58 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-09-13 21:05 [PATCH] arm: remove unused code in delay.S Felipe Contreras
2009-09-13 21:28 ` Marek Vasut
2009-09-13 23:00 ` Russell King - ARM Linux
2009-09-14 0:21 ` Jamie Lokier
2009-09-14 8:10 ` Russell King - ARM Linux
2009-09-14 12:58 ` Felipe Contreras [this message]
2009-09-14 14:00 ` Russell King - ARM Linux
2009-09-14 14:38 ` Felipe Contreras
2009-09-14 14:40 ` Russell King - ARM Linux
2009-09-14 15:14 ` Felipe Contreras
2009-09-14 15:21 ` Russell King - ARM Linux
2009-09-14 15:50 ` Felipe Contreras
2009-09-14 16:25 ` Marek Vasut
2009-09-14 16:54 ` Felipe Contreras
2009-09-14 15:36 ` Wolfram Sang
2009-09-14 16:06 ` Felipe Contreras
2009-09-14 16:24 ` Wolfram Sang
2009-09-15 10:37 ` Pavel Machek
2009-09-15 10:47 ` Felipe Contreras
2009-09-15 10:49 ` Pavel Machek
2009-09-15 11:20 ` Felipe Contreras
2009-09-15 12:29 ` Steve Chen
2009-09-15 13:41 ` Marek Vasut
2009-09-15 16:30 ` Steve Chen
2009-09-15 18:58 ` Felipe Contreras
2009-09-15 19:44 ` Steve Chen
2009-09-15 20:39 ` Marek Vasut
2009-09-15 21:04 ` Krzysztof Halasa
2009-09-15 22:26 ` Steve Chen
2009-09-15 22:47 ` Krzysztof Halasa
2009-09-16 8:26 ` Steve Chen
2009-09-16 12:30 ` Krzysztof Halasa
2009-09-16 14:49 ` Steve Chen
2009-09-16 20:21 ` Sergei Shtylyov
2009-09-16 13:47 ` Russell King - ARM Linux
2009-09-17 19:32 ` Jamie Lokier
2009-09-17 19:41 ` Russell King - ARM Linux
2009-09-17 21:29 ` [PATCH v2] " Steve Chen
2009-09-17 21:37 ` Jamie Lokier
2009-09-17 22:25 ` Steve Chen
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