[RFC | PATCH] move device-specific private data out of tuner struct

[hermann-pitton at arcor.de (hermann pitton)]

Am Dienstag, den 29.05.2007, 22:19 -0400 schrieb Michael Krufky:
> Markus Rechberger wrote:
> > On 5/29/07, Mauro Carvalho Chehab <mchehab at infradead.org> wrote:
> >> Em Ter, 2007-05-29 ?s 16:38 -0400, Michael Krufky escreveu:
> >> > As it stands currently, all device-specific data for analog tuner
> >> > drivers are stored in the main tuner struct.  This is a potential
> >> waste
> >> > of memory for tuner drivers that do not utilize all of these
> >> structures.
> >> >
> >> > Up until now, as the needs of the drivers have changed, a developer
> >> > would issue an RFC to explain what he needs to add to the tuner struct
> >> > in order to handle the necessary change for the driver in question.
> >> > With these private structures moved out of the main tuner struct, such
> >> > changes in the future would only affect the specific tuner driver.
> >> >
> >> > I have written a driver for the Philips / NXP TDA18271 silicon tuner.
> >> > This driver needs to maintain a snapshot of the register values in
> >> > memory -- this would be a waste of space for the other tuner
> >> drivers, as
> >> > this space would only be needed for the tda18271.  Since this
> >> memory is
> >> > only needed for the TDA18271, it makes sense that it should be
> >> stored in
> >> > a private area specific to the TDA18271, only.
> >> >
> >> > The attached patch allocates these private structures on an as-needed
> >> > basis, within the object code for that specific tuner, rather than
> >> > globally inside the main tuner structure.  This change could also be
> >> > considered as a cleanup / overhaul, which brings the tuner.ko module
> >> > closer to an object-oriented design.
> >> >
> >> > Would anybody have any issues with this patch, if it were applied?
> >>
> >> The patch looks sane and it is really a good idea. Of course, it should
> >> be tested on all touched tuners.
> >>
> >
> > this is a good change yes.
> >
> > Markus
> Mauro & Markus,
> 
> Thanks for the feedback -- I've already tested this on the tda8290 +
> 8275, and on a tin can tuner (LG-H064F) using a tda9887 ...  The only
> tuner driver affected by this change that hasn't been tested yet is
> mt20xx.  Does anybody have a card using mt20xx that can test this?
> 
> It should be safe to push it into the master branch and -mm , to achieve
> sufficient testing before the 2.6.23 merge window opens, which should be
> months away.
> 
> For now, I've pushed the changeset to this tree:
> 
> http://linuxtv.org/hg/~mkrufky/tuner
> 
> - tuner: Move device-specific private data out of tuner struct
> 
>  drivers/media/video/mt20xx.c     |   33 +++++++++---
>  drivers/media/video/tda8290.c    |  105
> ++++++++++++++++++++++++---------------
>  drivers/media/video/tda9887.c    |   37 ++++++++-----
>  drivers/media/video/tuner-core.c |   10 +++
>  include/media/tuner.h            |   13 ----
>  5 files changed, 124 insertions(+), 74 deletions(-)
> 
> Cheers,
> 
> Mike
> 

Michael,

it seems there is a real problem and me doing only user level debug
can't resolve it.

Markus seems to think he can force his work over Mauro.

It doesn't work.

Forwarded mail follows.

Hermann