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From: "Ardelean, Alexandru" <alexandru.Ardelean@analog.com>
To: "jic23@kernel.org" <jic23@kernel.org>,
	"lars@metafoo.de" <lars@metafoo.de>
Cc: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"linux-iio@vger.kernel.org" <linux-iio@vger.kernel.org>
Subject: Re: [RFC PATCH 00/14] iio: buffer: add support for multiple buffers
Date: Mon, 11 May 2020 13:03:55 +0000	[thread overview]
Message-ID: <554fe46f0cdd1cafb313f534c0edd93f5686b806.camel@analog.com> (raw)
In-Reply-To: <c88b17c3-a9d6-e755-04e8-bc9f225e2a3b@metafoo.de>

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@metafoo.de> 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?


> 
> > My concern regarding going to use stuff from core [like
> > device_get_devnode()] is
> > that it seems to bypass some layers of kernel.
> > If I do 'git grep device_get_devnode', I get:
> > 
> > drivers/base/core.c:            name = device_get_devnode(dev, &mode, &uid,
> > &gid, &tmp);
> > drivers/base/core.c: * device_get_devnode - path of device node file
> > drivers/base/core.c:const char *device_get_devnode(struct device *dev,
> > drivers/base/devtmpfs.c:        req.name = device_get_devnode(dev,
> > &req.mode,
> > &req.uid, &req.gid, &tmp);
> > drivers/base/devtmpfs.c:        req.name = device_get_devnode(dev, NULL,
> > NULL,
> > NULL, &tmp);
> > include/linux/device.h:extern const char *device_get_devnode(struct device
> > *dev,
> > (END)
> > 
> > So, basically, most uses of device_get_devnode() are in core code, and I
> > feel
> > that this may be sanctioned somewhere by some core people, if I do it.
> > I could be wrong, but if you disagree, I'll take your word for it.
> You are not supposed to use the function itself, you should implement 
> the devnode() callback for the IIO bus, which is then used by the core 
> device_get_devnode() function.
> 

  reply	other threads:[~2020-05-11 13:04 UTC|newest]

Thread overview: 39+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-08 13:53 [RFC PATCH 00/14] iio: buffer: add support for multiple buffers Alexandru Ardelean
2020-05-08 13:53 ` [RFC PATCH 01/14] iio: Move scan mask management to the core Alexandru Ardelean
2020-05-08 13:53 ` [RFC PATCH 02/14] iio: hw_consumer: use new scanmask functions Alexandru Ardelean
2020-05-08 13:53 ` [RFC PATCH 03/14] iio: buffer: add back-ref from iio_buffer to iio_dev Alexandru Ardelean
2020-05-08 13:53 ` [RFC PATCH 04/14] iio: core,buffer: wrap iio_buffer_put() call into iio_buffers_put() Alexandru Ardelean
2020-05-08 13:53 ` [RFC PATCH 05/14] iio: core: register chardev only if needed Alexandru Ardelean
2020-05-24 16:40   ` Jonathan Cameron
2020-05-08 13:53 ` [RFC PATCH 06/14] iio: buffer,event: duplicate chardev creation for buffers & events Alexandru Ardelean
2020-05-08 13:53 ` [RFC PATCH 07/14] iio: core: add simple centralized mechanism for ioctl() handlers Alexandru Ardelean
2020-05-24 16:45   ` Jonathan Cameron
2020-05-25  7:24     ` Ardelean, Alexandru
2020-05-08 13:53 ` [RFC PATCH 08/14] iio: core: use new common ioctl() mechanism Alexandru Ardelean
2020-05-24 16:47   ` Jonathan Cameron
2020-05-25  7:27     ` Ardelean, Alexandru
2020-05-31 15:20       ` Jonathan Cameron
2020-05-08 13:53 ` [RFC PATCH 09/14] iio: buffer: split buffer sysfs creation to take buffer as primary arg Alexandru Ardelean
2020-05-24 16:49   ` Jonathan Cameron
2020-05-25  7:28     ` Ardelean, Alexandru
2020-05-31 15:21       ` Jonathan Cameron
2020-05-08 13:53 ` [RFC PATCH 10/14] iio: buffer: remove attrcount_orig var from sysfs creation Alexandru Ardelean
2020-05-08 13:53 ` [RFC PATCH 11/14] iio: buffer: add underlying device object and convert buffers to devices Alexandru Ardelean
2020-05-08 13:53 ` [RFC PATCH 12/14] iio: buffer: symlink the scan_elements dir back into IIO device's dir Alexandru Ardelean
2020-05-08 13:53 ` [RFC PATCH 13/14] iio: unpack all iio buffer attributes correctly Alexandru Ardelean
2020-05-24 17:28   ` Jonathan Cameron
2020-05-08 13:53 ` [RFC PATCH 14/14] iio: buffer: convert single buffer to list of buffers Alexandru Ardelean
2020-05-09  8:52 ` [RFC PATCH 00/14] iio: buffer: add support for multiple buffers Lars-Peter Clausen
2020-05-10 10:09   ` Jonathan Cameron
2020-05-11 10:33     ` Ardelean, Alexandru
2020-05-11 10:37       ` Lars-Peter Clausen
2020-05-11 13:03         ` Ardelean, Alexandru [this message]
2020-05-11 13:24           ` Ardelean, Alexandru
2020-05-11 13:58             ` Lars-Peter Clausen
2020-05-11 14:56               ` Ardelean, Alexandru
2020-05-11 19:56                 ` Lars-Peter Clausen
2020-05-12  6:26                   ` Ardelean, Alexandru
2020-05-16 13:08                     ` Ardelean, Alexandru
2020-05-16 16:24                       ` Jonathan Cameron
2020-05-17  6:26                         ` Ardelean, Alexandru
2020-05-17 13:40                           ` Jonathan Cameron

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