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SubjectRe: Backlight and LCD module patches [2]
On 09/05/04 10:00:32, Greg KH wrote:
> On Sat, Aug 21, 2004 at 02:51:33AM +0000, John Lenz wrote:
> >
> > Here. A few notes on the implementation. I have a global lock
> protecting
> > all match operations because otherwise we get a dining philosophers
> problem.
> > (Say the same class is in two class_match structures, class1 in the
> first
> > one and class2 in the second...)
>
> You also have some duplicated code in one function, which implies that
> you didn't test this patch (it's in the updated patch you sent me too) :)

I didn't test it. It was only to show what I was thinking of with
class_match.

>
> > The bigger question of how should we be linking these together in the
> first
> > place?
>
> I thought you only wanted the ability to actually find the different
> class devices. Then the code would take it from there. Not this
> complex driver core linking logic that you implemented.
>
> > Instead of using this class_match stuff, we could use class_interface.
>
> Exactly. Why don't you all use that instead?

The only benifit from class_match is the "object oriented approach". I
assume that the struct list_head children in struct class can be used from
driver code? It is the correct policy to use that directly than to call a
function in class.c? As well, the struct kobject in class_device (which we
would use to create a symbolic link)? And of course our driver code would
have to acquire class->subsys.rwsem...

If we do it in lcdbase.c we can even solve the locking problem... that is,
we can always acquire class->subsys.rwsem in the lcd class before the
class->subsys.rwsem in fb_class.

John

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