Re: [RFC PATCH 00/12] iio: core,buffer: add support for multiple IIO buffers per IIO device

From: Alexandru Ardelean
Date: Mon Nov 23 2020 - 08:03:56 EST


On Sat, Nov 21, 2020 at 8:53 PM Jonathan Cameron <jic23@xxxxxxxxxx> wrote:
>
> On Tue, 17 Nov 2020 18:23:28 +0200
> Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx> wrote:
>
> > Continuing from:
> > https://lore.kernel.org/linux-iio/20200517144023.6c5cb169@archlinux/
> >
> > This is a V2 of the initial attempt in the discussion above.
> > But it did not occur to me that I should mark it as V2 when I generated
> > the patches.
> > I've only tested [so far] that the current IIO buffer mechnism still works.
> > And decided to show this sketch patchset.
> >
> > This requires the ioctl() centralization mechanism, for which I sent a
> > fix earlier.
> > https://lore.kernel.org/linux-iio/CA+U=Dsqf3UgyM666Gg9EmehpWiucDx2P0bmsC9JR--JJDT_eWQ@xxxxxxxxxxxxxx/T/#t
> > https://lore.kernel.org/linux-iio/20201117095154.7189-1-alexandru.ardelean@xxxxxxxxxx/T/#u
> >
> > The gist of this is that now, the first IIO buffer should work as
> > before, but all extra buffers should go through the anon inodes
> > mechanism.
> > I'd need to find a device or a way or a chip to test these extra buffers
> > stuff. But I'm confident that this current form should eventually work
> > with multiple IIO buffers per 1 IIO device and with anon inodes.
> >
> > Maybe I'll take some of the patches in this set separately and send them
> > individually. The problem with patchsets like this that tackle changes
> > in a framework (like IIO) is that I become unsure after the 5th-7th patch,
> > that the approach is correct. And I get even more unsure after that.
> >
> > I'll create some userspace code to test this a bit, but I thought I'd
> > send an RFC in the meantime.
>
> From a first read, with all the warnings you give above, this looks pretty
> good to me. The kobj stuff is a little nasty and needs more docs
> but other than that it all looks quite pleasant and readable and was
> roughly what I was expecting from earlier discussions (which is great!).
>
> Good work on this, looking forward to next steps.

Thanks.
I'll see about re-spinning this.
With the iio_buffer_set_attrs() change merged, this patchset has a
new context that I need to take a look at.

>
> Jonathan
>
> >
> > Alexandru Ardelean (12):
> > iio: core: register chardev only if needed
> > iio: buffer: add back-ref from iio_buffer to iio_dev
> > iio: buffer: rework buffer & scan_elements dir creation
> > iio: buffer: add index to the first IIO buffer dir and symlink it back
> > iio: core: split __iio_device_attr_init() to init only the attr object
> > iio: buffer: re-route scan_elements via it's kobj_type
> > iio: buffer: re-route core buffer attributes via it's new kobj_type
> > iio: buffer: add helper to get the IIO device to which a buffer
> > belongs
> > iio: re-route all buffer attributes through new buffer kobj_type
> > iio: core: wrap iio device & buffer into struct for character devices
> > iio: buffer: introduce support for attaching more IIO buffers
> > iio: buffer: add ioctl() to support opening extra buffers for IIO
> > device
> >
> > drivers/iio/accel/adxl372.c | 36 +-
> > drivers/iio/accel/bmc150-accel-core.c | 34 +-
> > drivers/iio/adc/at91-sama5d2_adc.c | 30 +-
> > .../buffer/industrialio-buffer-dmaengine.c | 13 +-
> > .../cros_ec_sensors/cros_ec_sensors_core.c | 30 +-
> > .../common/hid-sensors/hid-sensor-trigger.c | 32 +-
> > drivers/iio/iio_core.h | 11 +
> > drivers/iio/industrialio-buffer.c | 582 ++++++++++++++----
> > drivers/iio/industrialio-core.c | 117 ++--
> > include/linux/iio/buffer.h | 2 +
> > include/linux/iio/buffer_impl.h | 25 +-
> > include/linux/iio/iio-opaque.h | 6 +
> > include/linux/iio/iio.h | 2 +-
> > include/linux/iio/sysfs.h | 50 ++
> > include/uapi/linux/iio/buffer.h | 16 +
> > 15 files changed, 735 insertions(+), 251 deletions(-)
> > create mode 100644 include/uapi/linux/iio/buffer.h
> >
>