From: marex@denx.de (Marek Vasut)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH] IIO: Add basic MXS LRADC driver
Date: Thu, 19 Jul 2012 21:26:31 +0200 [thread overview]
Message-ID: <201207192126.31772.marex@denx.de> (raw)
In-Reply-To: <50081AC0.10703@metafoo.de>
Dear Lars-Peter Clausen,
> On 07/19/2012 04:23 PM, Marek Vasut wrote:
> > Dear Lars-Peter Clausen,
> >
> > Sorry for my late reply, got busy with other crazy stuff.
> >
> > [...]
> >
> >>>> Is there any reason not to use the mxs_lradc struct directly has the
> >>>> iio data?
> >>>
> >>> I explained it below in the patch. I hope we'll eventually support the
> >>> delay triggers, which will need 4 separate IIO devices. And this is
> >>> where this structure will be augmented by other components.
> >>
> >> Ok I saw the comment, but it wasn't obvious to me that delay channels
> >> will require multiple IIO devices. Might make sense to state this
> >> explicitly.
> >
> > Fixed.
> >
> >>>>> [...]
> >>>>>
> >>>>> +
> >>>>> +/*
> >>>>> + * Channel management
> >>>>> + *
> >>>>> + * This involves crazy mapping between 8 virtual channels the CTRL4
> >>>>> register + * can harbor and 16 channels total this hardware supports.
> >>>>> + */
> >>>>
> >>>> I suppose this means only a maximum 8 channels can be active at a
> >>>> time. I've recently posted a patch which makes it easy to implement
> >>>> such a restriction.
> >>>> http://www.spinics.net/lists/linux-iio/msg05936.html and
> >>>> http://www.spinics.net/lists/linux-iio/msg05935.html for an example
> >>>> validate callback implementation. In your case you'd check for
> >>>> bitmap_weight(...) <= 8. Those patches are not yet in IIO though.
> >>>
> >>> This is good. When do you expect this to hit linux-next possibly? Or at
> >>> least linux-iio?
> >>
> >> soon, hopefully.
> >
> > So I checked this, not sure how it'll help me though.
>
> Right now with your driver you can enable any combination of channels. If
> more than 8 channels are enabled and you start sampling it will fail, since
> not all channels can be mapped. With those patch you can implement a
> validate callback and check for bitmap_weight(scan_mask) <= 8. This will
> ensure that it is not possible to select more than 8 channels at once,
> which again means that starting sampling can't fail of this.
Ok, I fixed this one. One last thing that I don't really understand is this. I
run generic_buffer.c to source samples from the LRADC. Is there any way to
continuously sample them? Because right now, I get one sample and that's it, no
more samples happen later on (I can 0 data in subsequent read() call).
Best regards,
Marek Vasut
next prev parent reply other threads:[~2012-07-19 19:26 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-04 2:15 [PATCH] IIO: Add basic MXS LRADC driver Marek Vasut
2012-07-04 4:30 ` Wolfgang Denk
2012-07-04 8:35 ` Lars-Peter Clausen
2012-07-04 23:48 ` Marek Vasut
2012-07-05 8:33 ` Lars-Peter Clausen
2012-07-05 19:53 ` Marek Vasut
2012-07-19 14:23 ` Marek Vasut
2012-07-19 14:33 ` Lars-Peter Clausen
2012-07-19 15:15 ` Marek Vasut
2012-07-19 19:26 ` Marek Vasut [this message]
2012-07-20 2:18 ` Marek Vasut
2012-07-20 8:39 ` Robert Schwebel
2012-07-20 11:32 ` Marek Vasut
2012-07-20 14:09 ` Lars-Peter Clausen
2012-07-22 19:48 ` Jonathan Cameron
2012-07-20 14:11 ` Lars-Peter Clausen
2012-07-20 15:12 ` Marek Vasut
2012-07-09 9:19 ` Juergen Beisert
2012-07-09 9:52 ` Lars-Peter Clausen
2012-07-09 10:03 ` Marek Vasut
2012-07-10 9:20 ` Juergen Beisert
2012-07-10 9:26 ` Marek Vasut
2012-07-10 9:49 ` Juergen Beisert
2012-07-10 10:08 ` Marek Vasut
2012-07-10 10:26 ` Juergen Beisert
2012-07-10 10:35 ` Lars-Peter Clausen
2012-07-10 10:41 ` Juergen Beisert
2012-07-10 10:45 ` Marek Vasut
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