Subject: Re: [PATCH 5/7] Celleb: Supports VFD on Celleb 2

From: Arnd Bergmann <[email-masked]>
Date: Thu, 27 Sep 2007 11:07:33 +0200

On Thursday 27 September 2007, Ishizaki Kou wrote:
> This is a patch to support VFD on Celleb 2.
> VFD is a small LCD to show miscellaneous messages.
> 
> Signed-off-by: Kou Ishizaki <[email-masked]>

The implementation looks fine, but I'm not sure if /proc/ppc64/rtas is the
right way to do it. The two problems I have with this are:

* /proc files are generally not a good idea for new stuff. We carry around
  the existing /proc/ppc64/rtas files because we can't change the interface
  for existing stuff. My feeling is that your interface should better be
  implemented as a character device, or be integrating into some other
  existing message interface, if we can find one.

* The firmware seems to implement the generic rtas interface for
  display-character and set-indicator, but your driver is celleb specific.
  I'd be feel more comfortable if we could come up with a driver that also
  works on other systems that implement the same rtas calls.

	Arnd <><