On Mon, 2020-05-11 at 21:56 +0200, Lars-Peter Clausen wrote: > [External] > > On 5/11/20 4:56 PM, Ardelean, Alexandru wrote: > > On Mon, 2020-05-11 at 15:58 +0200, Lars-Peter Clausen wrote: > > > [External] > > > > > > On 5/11/20 3:24 PM, Ardelean, Alexandru wrote: > > > > On Mon, 2020-05-11 at 13:03 +0000, Ardelean, Alexandru wrote: > > > > > [External] > > > > > > > > > > On Mon, 2020-05-11 at 12:37 +0200, Lars-Peter Clausen wrote: > > > > > > [External] > > > > > > > > > > > > On 5/11/20 12:33 PM, Ardelean, Alexandru wrote: > > > > > > > On Sun, 2020-05-10 at 11:09 +0100, Jonathan Cameron wrote: > > > > > > > > [External] > > > > > > > > > > > > > > > > On Sat, 9 May 2020 10:52:14 +0200 > > > > > > > > Lars-Peter Clausen <lars@xxxxxxxxxx> wrote: > > > > > > > > > > > > > > > > > On 5/8/20 3:53 PM, Alexandru Ardelean wrote: > > > > > > > > > > [...] > > > > > > > > > > What I don't like, is that iio:device3 has iio:buffer3:0 (to > > > > > > > > > > 3). > > > > > > > > > > This is because the 'buffer->dev.parent = &indio_dev->dev'. > > > > > > > > > > But I do feel this is correct. > > > > > > > > > > So, now I don't know whether to leave it like that or > > > > > > > > > > symlink to > > > > > > > > > > shorter > > > > > > > > > > versions like 'iio:buffer3:Y' -> 'iio:device3/bufferY'. > > > > > > > > > > The reason for naming the IIO buffer devices to > > > > > > > > > > 'iio:bufferX:Y' > > > > > > > > > > is > > > > > > > > > > mostly to make the names unique. It would have looked weird > > > > > > > > > > to > > > > > > > > > > do > > > > > > > > > > '/dev/buffer1' if I would have named the buffer devices > > > > > > > > > > 'bufferX'. > > > > > > > > > > > > > > > > > > > > So, now I'm thinking of whether all this is acceptable. > > > > > > > > > > Or what is acceptable? > > > > > > > > > > Should I symlink 'iio:device3/iio:buffer3:0' -> > > > > > > > > > > 'iio:device3/buffer0'? > > > > > > > > > > What else should I consider moving forward? > > > > > > > > > > What means forward? > > > > > > > > > > Where did I leave my beer? > > > > > > > > > Looking at how the /dev/ devices are named I think we can > > > > > > > > > provide > > > > > > > > > a > > > > > > > > > name > > > > > > > > > that is different from the dev_name() of the device. Have a > > > > > > > > > look > > > > > > > > > at > > > > > > > > > device_get_devnode() in drivers/base/core.c. We should be able > > > > > > > > > to > > > > > > > > > provide the name for the chardev through the devnode() > > > > > > > > > callback. > > > > > > > > > > > > > > > > > > While we are at this, do we want to move the new devices into > > > > > > > > > an > > > > > > > > > iio > > > > > > > > > subfolder? So iio/buffer0:0 instead of iio:buffer0:0? > > > > > > > > Possibly on the folder. I can't for the life of me remember why > > > > > > > > I > > > > > > > > decided > > > > > > > > not to do that the first time around - I'll leave it at the > > > > > > > > mysterious "it may turn out to be harder than you'd think..." > > > > > > > > Hopefully not ;) > > > > > > > I was also thinking about the /dev/iio subfolder while doing this. > > > > > > > I can copy that from /dev/input > > > > > > > They seem to do it already. > > > > > > > I don't know how difficult it would be. But it looks like a good > > > > > > > precedent. > > > > > > All you have to do is return "iio/..." from the devnode() callback. > > > > > I admit I did not look closely into drivers/input/input.c before > > > > > mentioning > > > > > this > > > > > as as good precedent. > > > > > > > > > > But, I looks like /dev/inpput is a class. > > > > > While IIO devices are a bus_type devices. > > > > > Should we start implementing an IIO class? or? > > > > What I should have highlighted [before] with this, is that there is no > > > > devnode() > > > > callback for the bus_type [type]. > > > But there is one in device_type :) > > Many thanks :) > > That worked nicely. > > > > I now have: > > > > root@analog:~# ls /dev/iio/* > > /dev/iio/iio:device0 /dev/iio/iio:device1 > > > > /dev/iio/device3: > > buffer0 buffer1 buffer2 buffer3 > > > > /dev/iio/device4: > > buffer0 > > > > > > It looks like I can shift these around as needed. > > This is just an experiment. > > I managed to move the iio devices under /dev/iio, though probably the IIO > > devices will still be around as /dev/iio:deviceX for legacy reasons. > > > > Two things remain unresolved. > > 1. The name of the IIO buffer device. > > > > root@analog:/sys/bus/iio/devices# ls iio\:device3/ > > buffer in_voltage0_test_mode name > > events in_voltage1_test_mode of_node > > iio:buffer:3:0 in_voltage_sampling_frequency power > > iio:buffer:3:1 in_voltage_scale scan_elements > > iio:buffer:3:2 in_voltage_scale_available subsystem > > iio:buffer:3:3 in_voltage_test_mode_available uevent > > > > > > Right now, each buffer device is named 'iio:buffer:X:Y'. > > One suggesttion was 'iio:deviceX:bufferY' > > I'm suspecting the latter is preferred as when you sort the folders, buffers > > come right after the iio:deviceX folders in /sys/bus/iio/devices. > > > > I don't feel it matters much the device name of the IIO buffer if we symlink > > it > > to a shorter form. > > > > I'm guessing, we symlink these devices to short-hand 'bufferY' folders in > > each > > 'iio:deviceX'? > > I think that would be a bit excessive. Only for the legacy buffer we > need to have a symlink. > > > [...] > > 2. I know this is [still] stupid now; but any suggestions one how to symlink > > /dev/iio:device3 -> /dev/iio/device3/buffer0 ? > > > Does not seem to be possible. Userspace will have to take care of it. > This means we need to keep legacy devices in /dev/ and only new buffers > in /dev/iio/. One thought about this, was that we keep the chardev for the IIO device for this. i.e. /dev/iio:deviceX and /dev/iio/deviceX/buffer0 open the same buffer. This means that for a device with 4 buffers, you get 5 chardevs. This also seems a bit much/excessive. Maybe also in terms of source-code. It would at least mean not moving the event-only chardev to 'industrialio- event.c', OR move it, and have the same chardev in 3 places ['industrialio- event.c', 'industrialio-buffer.c' & 'industrialio-buffer.c' Maybe this sort-of makes sense to have for a few years/kernel-revisions until things clean-up. I guess at this point, the maintainer should have the final say about this. > >
