From: Detlev Zundel <dzu@denx.de>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH] arm: Kirkwood: Add memory barriers to kwgbe_send/recv
Date: Wed, 01 Jul 2009 18:56:18 +0200 [thread overview]
Message-ID: <m2my7oqr4d.fsf@ohwell.denx.de> (raw)
In-Reply-To: <20090701171615.2d23daf7@marrow.netinsight.se> (Simon Kagstrom's message of "Wed, 1 Jul 2009 17:16:15 +0200")
Hi Simon,
> Add memory barriers to kwgbe_send/recv
>
> kwgbe_send/recv both have loops waiting for the hardware to set a bit.
> GCC 4.3.3 cleverly optimizes this to ... a while(1); loop. This patch
> introduces memory barriers to force re-loading of the transmit descriptor.
>
> mb() wasn't defined for arm, but perhaps it should?
You should rather use read/write accessor macros which "do the right
thing". Try using readl() for the loop. Memory barriers do not belong
into "upper level" code.
Cheers
Detlev
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next prev parent reply other threads:[~2009-07-01 16:56 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-01 15:16 [U-Boot] [PATCH] arm: Kirkwood: Add memory barriers to kwgbe_send/recv Simon Kagstrom
2009-07-01 16:56 ` Detlev Zundel [this message]
2009-07-01 17:09 ` Stefan Roese
2009-07-01 17:14 ` Scott Wood
2009-07-03 9:15 ` Detlev Zundel
2009-07-01 16:57 ` Prafulla Wadaskar
2009-07-02 6:47 ` Simon Kagstrom
2009-07-02 8:12 ` Prafulla Wadaskar
2009-07-03 8:57 ` Detlev Zundel
2009-07-04 23:52 ` Wolfgang Denk
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