linux-kernel - Re: [RFC PATCH 00/14] iio: buffer: add support for multiple buffers

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Message-ID: <20200510110958.29046a18@archlinux>
Date:   Sun, 10 May 2020 11:09:58 +0100
From:   Jonathan Cameron <jic23@...nel.org>
To:     Lars-Peter Clausen <lars@...afoo.de>
Cc:     Alexandru Ardelean <alexandru.ardelean@...log.com>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 00/14] iio: buffer: add support for multiple buffers

On Sat, 9 May 2020 10:52:14 +0200
Lars-Peter Clausen <lars@...afoo.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 ;)

Do we want to make the naming a bit more self describing, something like
iio/device0:buffer0?  Given the legacy interface will be outside
the directory anyway, could even do

iio/device0/buffer0 with link to iio:device0
iio/device0/buffer1 with no legacy link.

Ah, the bikeshedding fun we have ahead of us!

I think this set is going to take too much thinking for a Sunday
so may take me a little while to do a proper review...
+ I have a few other side projects I want to hammer on today :)

Jonathan