Re: [PATCH 00/14] IIO: Move from staging to drivers/iio

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On 4/25/2012 12:47 PM, Lars-Peter Clausen wrote:
On 04/25/2012 12:04 PM, Jonathan Cameron wrote:
On 4/25/2012 10:00 AM, Lars-Peter Clausen wrote:
On 04/22/2012 02:13 PM, Jonathan Cameron wrote:
Hi All,

This series is mostly what was discussed in
IIO: move out of staging plan.

It sits on top of the series
Staging:iio: Cleanup and refactor pre multibuffer.
which has gone to Greg already.

However, a few things I'd neglected there came up and occur
before the final 3 patches that actually do the main movement.
Basically if we had just done the move we would have introduced
selection of elements not in staging by driver in staging.  This
breaks the rule that code in staging should not effect any that
isn't.  Hence I've flipped all the selects to the equivalent
depends on lines.
I think the rule is that non-staging code should not depend on staging code,
but I haven't heard yet that staging code shouldn't select non-staging.
Look around there are quite a few drivers already selecting elements that
in staging so I guess it's not an issue.  Will revert this change.
E.g. there is a lot of infrastructure and helper code which is not user
selectable. Not allowing this to be selected by staging drivers would make
those helper functions inaccessible to it. Most of lib/ for example.

And I think at least the buffer implementations falls into this category.
There is no point of including them in the kernel image, if we have no
driver using them. And in fact all except one driver do select them instead
of depending on them. I think the best is to make them non user selectable
and let drivers which need them depend on them.
Take into account that we don't actually want to go out of our way to stop
people building drivers out of tree.  So I'd rather keep these user
selectable if
nothing needs them.
In my opinion the rule of thumb should be to either let Kconfig items be
user-selectable and let drivers depend on them or let them be
non-user-selectable and let drivers select them, but ok.
Would be nice... maybe we'll make this decision sometime in the future...

Triggers are a bit of a different story here. While all drivers select them
instead of depending on them there is also a different group which depends
on the trigger infrastructure. Namely the standalone trigger implementations.

But with a dependency like 'depends on !IIO_BUFFER || IIO_TRIGGER' the
driver will be available without IIO_BUFFER being select or when both
IIO_BUFFER and IIO_TRIGGER are selected, but not if IIO_BUFFER is selected
and not IIO_TRIGGER. This is a bit confusing in my opinion.

One way to solve this would be to make IIO_BUFFER and IIO_TRIGGER more
tightly coupled. In reality we never really use one without the other, so
there is not much gain from making them selectable independently and may
even cause some confusion.
We do use the separately in all hardware buffers.  There triggers often
don't have
any meaning (or at least we can't get to them so no point in exposing
userspace interfaces).
I meant the generic trigger infrastructure (i.e. everything that's pulled in
by IIO_TRIGGER), not the individual trigger implementations. I think there
is only one driver with buffer support which does not depend on IIO_TRIGGER
(or selects it).
Probably true, but there are a few drivers that should be in this state and aren't either because they don't support buffers or do it horribly wrong (the impact sensor under
accel for starters with it's horrible binary sysfs files).

But for now we can just make the buffer implementation of drivers which have
optional buffer support depend on both IIO_BUFFER and IIO_TRIGGER.

i.e. 's/#ifdef CONFIG_IIO_BUFFER/if defined(CONFIG_IIO_BUFFER)&&

I can take care of this if you want to.
That would indeed be cleaner than the current stack of selects.  Would be
great if
you can do this.

So I'll drop my select->depends patches and move on with the rest of the move.
Clearly the change you suggest can stand separately anyway.
I think it is still worth converting 'select IIO_BUFFER' to 'depends
Sounds reasonable, but given the stage we are at in the merge cycle I've left this for

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