From: Arnd Bergmann <arnd@arndb.de>
To: ath9k-devel@lists.ath9k.org
Subject: [ath9k-devel] [PATCH 1/3] ath9k: Fix build error on ARM
Date: Tue, 04 Feb 2014 19:40:18 +0100 [thread overview]
Message-ID: <3469296.SINb5BZOG8@wuerfel> (raw)
In-Reply-To: <1391531796.2538.21.camel@joe-AO722>
On Tuesday 04 February 2014 08:36:36 Joe Perches wrote:
> On Tue, 2014-02-04 at 08:03 +0100, Holger Schurig wrote:
> > Joe, look in linux/arch/arm/include/asm/delay.h. The macro udelay
> > cannot handle large values because of lost-of-precision.
> >
> > IMHO udelay on ARM is broken, because it also cannot work with fast
> > ARM processors (where bogomips >= 3355, which is in sight now). It's
> > just not broken enought that someone did something against it ... so
> > the current kludge is good enought.
>
> Maybe something like this would be better?
>
I actually like the fact that we get link errors for insane 'udelay'
times. In most cases it's a driver bug because we shouldn't keep
the CPU busy for an eternity in the kernel (and call msleep() instead).
For the rare cases where mdelay makes sense, we also want to add
a comment to the code explaining why msleep cannot be used.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: Arnd Bergmann <arnd@arndb.de>
To: linux-arm-kernel@lists.infradead.org
Cc: Joe Perches <joe@perches.com>,
Holger Schurig <holgerschurig@gmail.com>,
Russell King <linux@arm.linux.org.uk>,
ath9k-devel <ath9k-devel@lists.ath9k.org>,
Sujith Manoharan <sujith@msujith.org>,
linux-wireless <linux-wireless@vger.kernel.org>,
John Linville <linville@tuxdriver.com>
Subject: Re: [ath9k-devel] [PATCH 1/3] ath9k: Fix build error on ARM
Date: Tue, 04 Feb 2014 19:40:18 +0100 [thread overview]
Message-ID: <3469296.SINb5BZOG8@wuerfel> (raw)
In-Reply-To: <1391531796.2538.21.camel@joe-AO722>
On Tuesday 04 February 2014 08:36:36 Joe Perches wrote:
> On Tue, 2014-02-04 at 08:03 +0100, Holger Schurig wrote:
> > Joe, look in linux/arch/arm/include/asm/delay.h. The macro udelay
> > cannot handle large values because of lost-of-precision.
> >
> > IMHO udelay on ARM is broken, because it also cannot work with fast
> > ARM processors (where bogomips >= 3355, which is in sight now). It's
> > just not broken enought that someone did something against it ... so
> > the current kludge is good enought.
>
> Maybe something like this would be better?
>
I actually like the fact that we get link errors for insane 'udelay'
times. In most cases it's a driver bug because we shouldn't keep
the CPU busy for an eternity in the kernel (and call msleep() instead).
For the rare cases where mdelay makes sense, we also want to add
a comment to the code explaining why msleep cannot be used.
Arnd
WARNING: multiple messages have this Message-ID (diff)
From: arnd@arndb.de (Arnd Bergmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [ath9k-devel] [PATCH 1/3] ath9k: Fix build error on ARM
Date: Tue, 04 Feb 2014 19:40:18 +0100 [thread overview]
Message-ID: <3469296.SINb5BZOG8@wuerfel> (raw)
In-Reply-To: <1391531796.2538.21.camel@joe-AO722>
On Tuesday 04 February 2014 08:36:36 Joe Perches wrote:
> On Tue, 2014-02-04 at 08:03 +0100, Holger Schurig wrote:
> > Joe, look in linux/arch/arm/include/asm/delay.h. The macro udelay
> > cannot handle large values because of lost-of-precision.
> >
> > IMHO udelay on ARM is broken, because it also cannot work with fast
> > ARM processors (where bogomips >= 3355, which is in sight now). It's
> > just not broken enought that someone did something against it ... so
> > the current kludge is good enought.
>
> Maybe something like this would be better?
>
I actually like the fact that we get link errors for insane 'udelay'
times. In most cases it's a driver bug because we shouldn't keep
the CPU busy for an eternity in the kernel (and call msleep() instead).
For the rare cases where mdelay makes sense, we also want to add
a comment to the code explaining why msleep cannot be used.
Arnd
next prev parent reply other threads:[~2014-02-04 18:40 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-02-04 3:07 [ath9k-devel] [PATCH 0/3] ath9k patches Sujith Manoharan
2014-02-04 3:07 ` Sujith Manoharan
2014-02-04 3:07 ` [ath9k-devel] [PATCH 1/3] ath9k: Fix build error on ARM Sujith Manoharan
2014-02-04 3:07 ` Sujith Manoharan
2014-02-04 3:34 ` [ath9k-devel] " Joe Perches
2014-02-04 3:34 ` Joe Perches
2014-02-04 3:40 ` [ath9k-devel] " Sujith Manoharan
2014-02-04 3:40 ` Sujith Manoharan
2014-02-04 7:03 ` [ath9k-devel] " Holger Schurig
2014-02-04 7:03 ` Holger Schurig
2014-02-04 12:59 ` [ath9k-devel] [PATCH] checkpatch: Add test for long udelay Joe Perches
2014-02-04 12:59 ` Joe Perches
2014-02-04 12:59 ` Joe Perches
2014-02-04 16:36 ` [ath9k-devel] [PATCH 1/3] ath9k: Fix build error on ARM Joe Perches
2014-02-04 16:36 ` Joe Perches
2014-02-04 16:36 ` Joe Perches
2014-02-04 18:40 ` Arnd Bergmann [this message]
2014-02-04 18:40 ` Arnd Bergmann
2014-02-04 18:40 ` Arnd Bergmann
2014-02-04 19:43 ` Joe Perches
2014-02-04 19:43 ` Joe Perches
2014-02-04 19:43 ` Joe Perches
2014-02-05 11:50 ` Russell King - ARM Linux
2014-02-05 11:50 ` Russell King - ARM Linux
2014-02-05 11:50 ` Russell King - ARM Linux
2014-02-05 12:32 ` Joe Perches
2014-02-05 12:32 ` Joe Perches
2014-02-05 12:32 ` Joe Perches
2014-02-05 12:41 ` Russell King - ARM Linux
2014-02-05 12:41 ` Russell King - ARM Linux
2014-02-05 12:41 ` Russell King - ARM Linux
2014-02-05 13:04 ` Joe Perches
2014-02-05 13:04 ` Joe Perches
2014-02-05 13:04 ` Joe Perches
2014-02-05 13:39 ` Russell King - ARM Linux
2014-02-05 13:39 ` Russell King - ARM Linux
2014-02-05 13:39 ` Russell King - ARM Linux
2014-02-05 14:03 ` Joe Perches
2014-02-05 14:03 ` Joe Perches
2014-02-05 14:03 ` Joe Perches
2014-02-05 14:21 ` Russell King - ARM Linux
2014-02-05 14:21 ` Russell King - ARM Linux
2014-02-05 14:21 ` Russell King - ARM Linux
2014-02-05 15:05 ` Joe Perches
2014-02-05 15:05 ` Joe Perches
2014-02-05 15:05 ` Joe Perches
2014-02-04 3:07 ` [ath9k-devel] [PATCH 2/3] ath9k: Do not support PowerSave by default Sujith Manoharan
2014-02-04 3:07 ` Sujith Manoharan
2014-02-04 3:07 ` [ath9k-devel] [PATCH 3/3] ath9k: Fix TX power calculation Sujith Manoharan
2014-02-04 3:07 ` Sujith Manoharan
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