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From: Vitor Soares <Vitor.Soares@synopsys.com>
To: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Jose Abreu <Jose.Abreu@synopsys.com>,
	Joao Pinto <Joao.Pinto@synopsys.com>,
	"arnd@arndb.de" <arnd@arndb.de>,
	"wsa@the-dreams.de" <wsa@the-dreams.de>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"bbrezillon@kernel.org" <bbrezillon@kernel.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"broonie@kernel.org" <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 15:32:55 +0000
Message-ID: <CH2PR12MB4216459E37F9AB1AAF0B2EFDAE160@CH2PR12MB4216.namprd12.prod.outlook.com> (raw)
In-Reply-To: <20200217155141.08e87b3f@collabora.com>

Hi Boris,

From: Boris Brezillon <boris.brezillon@collabora.com>
Date: Mon, Feb 17, 2020 at 14:51:41

> Hello Vitor,
> 
> 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.

My idea was to expose every device to user-space by default so we can 
test them without a driver (more or less the i2c use case) but as we 
agreed during the i3c subsystem only expose devices that doesn't have 
device driver.
I considered to have a uevent but to expose the devices by default it 
would required something generic, what I didn't figure out and tend to 
follow the i2c-dev module.

With this current approach even if a device has a driver we can unbind it 
through the Sysfs and have access from user space which I found useful 
for debug.

> 
> Regards,
> 
> Boris



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  parent reply index

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-01-29 12:17 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
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 [this message]
2020-02-17 15:52     ` Boris Brezillon
2020-02-17 17:37   ` Boris Brezillon

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