From: stefan.eletzhofer@eletztrick.de
To: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Cc: Greg KH <greg@kroah.com>, Andrew Morton <akpm@osdl.org>
Subject: Re: [PATCH] 2.6 I2C re-add i2c_get_client()
Date: Sun, 2 May 2004 17:08:15 +0200 [thread overview]
Message-ID: <20040502150815.GA32603@gonzo.local> (raw)
In-Reply-To: <20040502060109.GF31886@kroah.com>
On Sat, May 01, 2004 at 11:01:09PM -0700, Greg KH wrote:
> On Thu, Apr 29, 2004 at 04:06:57PM +0200, stefan.eletzhofer@eletztrick.de wrote:
> > Hi,
> > here's a patch which re-adds i2c_get_client() back to i2c_core.c.
> > That call was removed in 2003 because there were no users of that
> > function at that time.
> >
> > I think this call is needed for I2C chip drivers which provide functionality to
> > be used by other driver modules, for example RTC chips or EEPROMs. These chip
> > drivers tend to encapsulate raw i2c chip access and provide function calls
> > for other modulesi, for example via the i2c_driver->command() method.
> >
> > I tried to get the locking right, so please comment. The patch is
> > against 2.6.6-rc3 and works quite fine with my i2c rtc chip.
>
> Locking looks correct, but you also need to increment either the
> device's reference count, and/or the module reference count for the
> client.
I thought that would be the purpose of i2c_use_client(), like the comment
in linux/i2c.h suggests? That call also takes care of the ALLOW_USE flag.
i2c_use_client() increments both the drivers and the adapters module ref
count, if I see it correctly. Then it also increments the clients usage count,
after checking the ALLOW_MULTIPLE_USE flag.
Its counterpart is i2c_release_client().
>
> Care to fix that up?
>
> thanks,
>
> greg k-h
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--
Eletztrick Computing - Customized Linux Development
Stefan Eletzhofer, Marktstrasse 43, DE-88214 Ravensburg
http://www.eletztrick.de
next prev parent reply other threads:[~2004-05-02 15:08 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-04-29 14:06 [PATCH] 2.6 I2C re-add i2c_get_client() stefan.eletzhofer
2004-05-02 6:01 ` Greg KH
2004-05-02 15:08 ` stefan.eletzhofer [this message]
2004-05-07 22:30 ` Greg KH
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