Re: [PATCH 0/2] staging: comedi: per-file read/write subdevice choice

[Ian Abbott]

On 04/11/2014 18:44, Hartley Sweeten wrote:
> On Tuesday, November 04, 2014 11:09 AM, Ian Abbott wrote:
> > This series of patches adds a couple of ioctl codes to the Comedi core
> > to allow the current "read" and "write" subdevice to be changed after
> > opening the comedi device.  The current read and write subdevice
> > information is stored in file private data allocated for the lifetime of
> > the file object, so the notion of current "read" and "write" subdevice
> > is local to the file object and does not alter anything in the main
> > control structure for the comedi device.  An extra level of indirection
> > is now required to access the main control structure.
> >
> > I've tested the multiple "read" subdevice case using a modified version
> > of the "comedi_test" module (modifying it to clone the existing AI
> > subdevice), and a modified version of the "comedi_test" application
> > (part of the "comedilib" installation) modified to use the new ioctls.
> > There isn't any support in comedilib itself yet.
> >
> > 1) staging: comedi: prepare support for per-file read and write
> >     subdevices
> > 2) staging: comedi: add ioctls to set per-file read and write subdevice
> >
> >   drivers/staging/comedi/comedi.h          |   2 +
> >   drivers/staging/comedi/comedi_compat32.c |   2 +
> >   drivers/staging/comedi/comedi_fops.c     | 217 +++++++++++++++++++++++++++----
> >   3 files changed, 196 insertions(+), 25 deletions(-)
>
> Ian,
>
> If I understand this correctly, the user can now open the "comediX"
> device which will give then access to the default dev->read_subdev
> and dev->write_subdev. They can then use the new ioctls to change
> the read/write subdevice and use them without having the open the
> "comediX_subdY" devices.
>
> If this is correct it seems like a good idea.

That's correct.

> Reviewed-by: H Hartley Sweeten <hsweeten@xxxxxxxxxxxxxxxxxxx>

Thanks for the review!

> Also, does this mean we can get rid of comedi_alloc_subdevice_minor()
> and the "comediX_sudbY" stuff?

That would be a bit premature at this stage.  Maybe in a year or two.

--
-=( Ian Abbott @ MEV Ltd.    E-mail: <abbotti@xxxxxxxxx> )=-
-=(                          Web: http://www.mev.co.uk/  )=-
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