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Re: [patch] Generic time fixes

To: Wolfgang Denk <wd@denx.de>
Subject: Re: [patch] Generic time fixes
From: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Date: Tue, 22 Jul 2003 22:54:23 +0200 (MET DST)
Cc: Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org
In-reply-to: <20030722102109.ADB10C6D82@atlas.denx.de>
Organization: Technical University of Gdansk
Original-recipient: rfc822;linux-mips@linux-mips.org
Sender: linux-mips-bounce@linux-mips.org
On Tue, 22 Jul 2003, Wolfgang Denk wrote:

> > I share your dislike of updating the RTC for performance reasons; these
> 
> There are more problems with the 11 minute mode.  We  ran  into  this
> issue  for hard on some PowerPC systems. Assume a situation where the
> RTC is connected through a I2C  bus.  Problem  1:  normally  the  i2c
> drivers  will  be  loaded prety late, which means the system will run
> initially with an undefined time. Problem 2: on some  actions  a  i2c
> transfer  involves  programming an on-chip i2c controller, which will
> perform the task and then signal it's done by an interrupt. On such a
> system the 11 minute mode will crash the system because rtc_set  will
> be called from interrupt contect itself.
> 
> There was a  somewhat  controverse  discussion  on  the  linuxppc_dev
> mailing list, without a real solution.

 A possible solution is to make the update configurable with a sysctl.  It
really begs for it.  I think it may be worth discussing at the LKML. 
Additionally Ulrich Windl may wish to share a few thoughts on the matter. 

-- 
+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+--------------------------------------------------------------+
+        e-mail: macro@ds2.pg.gda.pl, PGP key available        +


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