From: Vitor Soares <Vitor.Soares@synopsys.com>
To: Boris Brezillon <boris.brezillon@collabora.com>,
Arnd Bergmann <arnd@arndb.de>
Cc: Jose Abreu <Jose.Abreu@synopsys.com>,
Joao Pinto <Joao.Pinto@synopsys.com>,
Wolfram Sang <wsa@the-dreams.de>,
gregkh <gregkh@linuxfoundation.org>,
Boris Brezillon <bbrezillon@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Mark Brown <broonie@kernel.org>,
"linux-i3c@lists.infradead.org" <linux-i3c@lists.infradead.org>
Subject: RE: [RFC v2 0/4] Introduce i3c device userspace interface
Date: Mon, 17 Feb 2020 15:55:08 +0000 [thread overview]
Message-ID: <CH2PR12MB42166ED8E84503B53340F80DAE160@CH2PR12MB4216.namprd12.prod.outlook.com> (raw)
In-Reply-To: <20200217163622.6c78fa3f@collabora.com>
Hi,
From: Boris Brezillon <boris.brezillon@collabora.com>
Date: Mon, Feb 17, 2020 at 15:36:22
> On Mon, 17 Feb 2020 16:06:45 +0100
> Arnd Bergmann <arnd@arndb.de> wrote:
>
> > On Mon, Feb 17, 2020 at 3:51 PM Boris Brezillon
> > <boris.brezillon@collabora.com> wrote:
> > > Sorry for taking so long to reply, and thanks for working on that topic.
> > >
> > > On Wed, 29 Jan 2020 13:17:31 +0100
> > > Vitor Soares <Vitor.Soares@synopsys.com> wrote:
> > >
> > > > For today there is no way to use i3c devices from user space and
> > > > the introduction of such API will help developers during the i3c device
> > > > or i3c host controllers development.
> > > >
> > > > The i3cdev module is highly based on i2c-dev and yet I tried to address
> > > > the concerns raised in [1].
> > > >
> > > > NOTES:
> > > > - The i3cdev dynamically request an unused major number.
> > > >
> > > > - The i3c devices are dynamically exposed/removed from dev/ folder based
> > > > on if they have a device driver bound to it.
> > >
> > > May I ask why you need to automatically bind devices to the i3cdev
> > > driver when they don't have a driver matching the device id
> > > loaded/compiled-in? If we get the i3c subsystem to generate proper
> > > uevents we should be able to load the i3cdev module and bind the device
> > > to this driver using a udev rule.
> >
> > I think that would require manual configuration to ensure that the correct
> > set of devices get bound to either the userspace driver or an in-kernel
> > driver.
>
> Hm, isn't that what udev is supposed to do anyway? Remember that
> I3C devices expose a manufacturer and part-id (which are similar to the
> USB vendor and product ids), so deciding when an I3C device should be
> bound to the i3cdev driver should be fairly easy, and that's a
> per-device decision anyway.
>
> > The method from the current patch series is more complicated,
> > but it means that any device can be accessed by the user space driver
> > as long as it's not already owned by a kernel driver.
>
> Well, I'm more worried about the extra churn this auto-binding logic
> might create for the common 'on-demand driver loading' use case. At
> first, there's no driver matching a specific device, but userspace
> might load one based on the uevents it receives. With the current
> approach, that means we'd first have to unbind the device before
> loading the driver. AFAICT, no other subsystem does that.
I'm about to finish v3 (today or tomorrow) and I think I fixed all
concerns rise during v2. I would like you to see that version before any
change.
Best regards,
Vitor Soares
_______________________________________________
linux-i3c mailing list
linux-i3c@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-i3c
next prev parent reply other threads:[~2020-02-17 16:45 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-29 12:17 [RFC v2 0/4] Introduce i3c device userspace interface Vitor Soares
2020-01-29 12:17 ` [RFC v2 1/4] i3c: master: export i3c_masterdev_type Vitor Soares
2020-02-17 14:56 ` Boris Brezillon
2020-02-17 14:59 ` Boris Brezillon
2020-01-29 12:17 ` [RFC v2 2/4] i3c: master: export i3c_bus_type symbol Vitor Soares
2020-01-29 12:17 ` [RFC v2 3/4] i3c: master: add i3c_for_each_dev helper Vitor Soares
2020-01-29 12:17 ` [RFC v2 4/4] i3c: add i3cdev module to expose i3c dev in /dev Vitor Soares
2020-01-29 14:30 ` Arnd Bergmann
2020-01-29 17:00 ` Vitor Soares
2020-01-29 19:39 ` Arnd Bergmann
2020-02-04 13:19 ` Vitor Soares
2020-02-17 15:26 ` Boris Brezillon
2020-02-17 14:51 ` [RFC v2 0/4] Introduce i3c device userspace interface Boris Brezillon
2020-02-17 15:06 ` Arnd Bergmann
2020-02-17 15:36 ` Boris Brezillon
2020-02-17 15:55 ` Vitor Soares [this message]
2020-02-17 16:03 ` gregkh
2020-02-17 16:12 ` Vitor Soares
2020-02-17 16:23 ` Boris Brezillon
2020-02-17 16:31 ` Arnd Bergmann
2020-02-17 17:06 ` Boris Brezillon
2020-02-17 16:19 ` Arnd Bergmann
2020-02-17 16:34 ` Boris Brezillon
2020-02-17 15:32 ` Vitor Soares
2020-02-17 15:52 ` Boris Brezillon
2020-02-17 17:37 ` Boris Brezillon
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=CH2PR12MB42166ED8E84503B53340F80DAE160@CH2PR12MB4216.namprd12.prod.outlook.com \
--to=vitor.soares@synopsys.com \
--cc=Joao.Pinto@synopsys.com \
--cc=Jose.Abreu@synopsys.com \
--cc=arnd@arndb.de \
--cc=bbrezillon@kernel.org \
--cc=boris.brezillon@collabora.com \
--cc=broonie@kernel.org \
--cc=gregkh@linuxfoundation.org \
--cc=linux-i3c@lists.infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=wsa@the-dreams.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).