Re: [PATCH] Add STMicroelectronics LPS001WP pressure sensor device driver into misc

[Jonathan Cameron <jic23@cam.ac.uk>]

On 03/15/11 12:51, Mark Brown wrote:
> On Tue, Mar 15, 2011 at 11:11:00AM +0000, Jonathan Cameron wrote:
>> On 03/15/11 09:38, Arnd Bergmann wrote:
> 
> [Reflowed Jonathan's text into 80 columns for legibility.]
> 
>>> Do you think it would help to split the iio codebase into a smaller part
>>> for the relatively clean drivers that can be put into shape for
>>> drivers/iio, and the bulk of the code that stays in staging for a bit
>>> longer, until it gets converted to the new one in small chunks?
> 
>> 1) Spit functionality out in staging. This would give a core set that
>> is basically the sysfs only stuff.  To do that we'd have to define a
>> struct iio_dev_basic and make it an element of the iio_dev.  Prior to
>> that we'd probably need to make pretty much all accesses into iio_dev
>> via macros / inline functions which would not be a trivial
>> undertaking.
> 
>> Then we could switch those drivers doing the minimum to the _basic
>> form.  At that point we could perhaps attempt to move a couple of
>> drivers and the abi docs out of staging.
> 
>> The disadvantages of this that come to mind are: * Makes the path to
>> driver addition that I'd prefer trickier.  You write a basic sysfs
>> only driver first, then add on stuff like events and buffering as
>> separate patches. We could go the other way around like v4l2-subdev
>> and have a base structure with the option of pointers to structures
>> offering different combinations of features.  * Not many of the
>> drivers I'd consider to be ready to go at the moment are actually in
>> this _basic class. 
> 
> For what it's worth I have a few drivers I'd like to do which fall into
> this category.  I've been put off working on them by the fact that I'm
> not seeing a route out of staging for the subsystem.
> 
>> 2) Basically make a copy.  This would look like the original patch set did when we went
> 
> A third option is just to lift everything out of staging roughly as it
> is now with anything that definitely needs redoing dropped, addressing
> any review comments for mainline but not doing much else, and then
> resume working on adding additional stuff.  It sounds like the userspace
> interfaces that are there at present are mostly OK and most of the
> issues are in-kernel?
Mostly, though I suspect our events interface will cause some 'discussion'
and that sits one step above the absolute minimum driver.

Right now I want to push out the rewrite of the triggers, then I'll start
putting together a patch set to try and move some stuff over and see how
well things break up.