From: LW@KARO-electronics.de (Lothar Waßmann)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] collie: don't read GPSR
Date: Fri, 17 Jun 2011 16:49:31 +0200 [thread overview]
Message-ID: <19963.27003.636701.332500@ipc1.ka-ro> (raw)
In-Reply-To: <1308319892-13057-1-git-send-email-dbaryshkov@gmail.com>
Hi,
Dmitry Eremin-Solenikov writes:
> On StrongARM GPSR is write-only according to docs, so don't read from
> it. Just set the required GPIO.
>
Anyway GPSR (and GPCR) is a bit oriented register that allows
asserting individual bits without the need for read-modify-write
cycles, making the access inherently multithread safe. Using
read-modify-write on this register is contrary to the HW design.
A quick grep of the kernel source shows another abuse like this in
drivers/video/sa1100fb.c: GPSR |= SHANNON_GPIO_DISP_EN;
drivers/video/sa1100fb.c: GPCR |= SHANNON_GPIO_DISP_EN;
Lothar Wa?mann
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next prev parent reply other threads:[~2011-06-17 14:49 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-17 14:11 [PATCH] collie: don't read GPSR Dmitry Eremin-Solenikov
2011-06-17 14:49 ` Lothar Waßmann [this message]
2011-06-17 15:07 ` Eric Miao
2011-06-17 15:35 ` Dmitry Eremin-Solenikov
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