linux-kernel - Re: [i2c] [PATCH 1/5] Implement module aliasing for i2c to translate from device tree names

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Date:	Sat, 12 Jan 2008 11:26:34 -0500
From:	"Jon Smirl" <jonsmirl@...il.com>
To:	"Jean Delvare" <khali@...ux-fr.org>
Cc:	linuxppc-dev@...abs.org, i2c@...sensors.org,
	linux-kernel@...r.kernel.org
Subject: Re: [i2c] [PATCH 1/5] Implement module aliasing for i2c to translate from device tree names

On 1/12/08, Jean Delvare <khali@...ux-fr.org> wrote:
> Hi Jon,
>
> On Fri, 11 Jan 2008 20:20:15 +0100, Jean Delvare wrote:
> > > +{
> > > +   /* only powerpc drivers implement the id_table,
> > > +    * it is empty on other platforms */
> > > +   if (id) {
> > > +           while (id->name[0]) {
> > > +                   if (strcmp(client->driver_name, id->name) == 0)
> >
> > This doesn't look right to me. You should be comparing client->name,
> > not client->driver_name, with id->name. Where id_table is implemented,
> > client->driver_name might not even be set. I see that the next patch in
> > the series makes use of client->driver_name as well, so your code
> > "works"... but this ain't correct still.
>
> Err, scratch this (and related comments), I just realized what you were
> trying to do. That's different from what I had in mind and so I read
> your code wrong. I'll read it (and test it) again not making this
> incorrect assumption and my comments will likely be different after
> that. Well, I still think that it needs to be changed a bit, but
> probably not in the direction I suggested at first (which, I realize
> now, has its own share of issues - so it's not fair to me to point you
> there.)

The common scheme used elsewhere in the kernel for handling more than
one device in a single driver is aliases. The i2c code's existing
driver_name/type combination is a different way of implementing the
same feature. But there is no real need for driver_name/type on any
platform if aliases are used. Back in version 10 or 11 I had code in
there which replaced the two fields with aliases on all platforms but
too many people objected so I removed it..

IMHO, driver_name/type should be removed in new style drivers and
replaced with aliases on all platforms since aliases are the standard
kernel mechanism.



>
> Sorry for the trouble. I'll post updated comments later today, but I'm
> also pretty busy with other issues, some of which need to be solved
> before 2.6.24 is released so I can't really delay them.
>
> --
> Jean Delvare
>


-- 
Jon Smirl
jonsmirl@...il.com
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