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From: Greg KH <greg@kroah.com>
To: kernelnewbies@kernelnewbies.org
Subject: Re: platform device as parent of a miscdevice
Date: Tue, 30 Mar 2021 22:09:09 +0200	[thread overview]
Message-ID: <YGOFZblQpF2Yt0G8@kroah.com> (raw)
In-Reply-To: <20210330192717.aua2loxmypqoehsp@viti.kaiser.cx>

On Tue, Mar 30, 2021 at 09:27:17PM +0200, Martin Kaiser wrote:
> > What in-kernel misc drivers do not do that that you feel should?
> 
> My misunderstanding was that quite a few drivers set the parent pointer
> but hardly anyone uses the parent pointer in the file_operations.

What parent pointer in struct file_operations?  I don't see one...

> It seems that most drivers have their miscdevice as part of their global
> structure and use container_of in the file_operations, e.g. ipmb_read in
> drivers/char/ipmi/ipmb_dev_int.c.

That's one way to use it, there are I think at least 3 ways to use it,
maybe more...

Don't confuse the struct device parent pointer with the private pointer
to get back to your local device-specific data.  They are different
things.

thanks,

greg k-h

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      reply	other threads:[~2021-03-30 20:09 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-30 16:04 platform device as parent of a miscdevice Martin Kaiser
2021-03-30 16:49 ` Greg KH
2021-03-30 19:27   ` Martin Kaiser
2021-03-30 20:09     ` Greg KH [this message]

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