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From: Pavel Machek <pavel@ucw.cz>
To: Hans Verkuil <hverkuil@xs4all.nl>
Cc: "Sakari Ailus" <sakari.ailus@iki.fi>,
	"Niklas Söderlund" <niklas.soderlund@ragnatech.se>,
	"Sakari Ailus" <sakari.ailus@linux.intel.com>,
	linux-media@vger.kernel.org, linux-leds@vger.kernel.org,
	laurent.pinchart@ideasonboard.com
Subject: Re: [RFC 00/19] Async sub-notifiers and how to use them
Date: Wed, 23 Aug 2017 13:34:36 +0200	[thread overview]
Message-ID: <20170823113436.GA1767@amd> (raw)
In-Reply-To: <ea92d79c-bba0-ca22-c0a7-0535d635729c@xs4all.nl>

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Hi!

> >> Is this always the case? In the R-Car VIN driver I register the video 
> >> devices using video_register_device() in the complete handler. Am I 
> >> doing things wrong in that driver? I had a patch where I moved the 
> >> video_register_device() call to probe time but it got shoot down in 
> >> review and was dropped.
> > 
> > I don't think the current implementation is wrong, it's just different
> > from other drivers; there's really no requirement regarding this AFAIU.
> > It's one of the things where no attention has been paid I presume.
> 
> It actually is a requirement: when a device node appears applications can
> reasonably expect to have a fully functioning device. True for any device
> node. You don't want to have to wait until some unspecified time before
> the full functionality is there.

Well... /dev/sdb appears, but you still get -ENOMEDIA before user
presses "Turn on USB storage" button on android phone.

So I agree it is not desirable, but it sometimes happens.

									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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  reply	other threads:[~2017-08-23 11:34 UTC|newest]

Thread overview: 50+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-07-18 19:03 [RFC 00/19] Async sub-notifiers and how to use them Sakari Ailus
2017-07-18 19:03 ` [RFC 01/19] device property: Introduce fwnode_property_get_reference_args Sakari Ailus
2017-07-18 19:03 ` [RFC 02/19] v4l: async: add subnotifier registration for subdevices Sakari Ailus
2017-07-18 21:28   ` Niklas Söderlund
2017-07-18 19:03 ` [RFC 03/19] dt: bindings: Add a binding for flash devices associated to a sensor Sakari Ailus
2017-07-18 19:03 ` [RFC 04/19] dt: bindings: Add lens-focus binding for image sensors Sakari Ailus
2017-07-28  8:53   ` Hans Verkuil
2017-07-28 12:45     ` Pavel Machek
2017-08-15 11:24     ` Sakari Ailus
2017-07-18 19:03 ` [RFC 05/19] leds: as3645a: Add LED flash class driver Sakari Ailus
2017-07-19 20:17   ` Jacek Anaszewski
2017-07-19 21:21     ` Sakari Ailus
2017-07-18 19:03 ` [RFC 06/19] leds: as3645a: Separate flash and indicator LED sub-devices Sakari Ailus
2017-07-18 19:03 ` [RFC 07/19] v4l: fwnode: Support generic parsing of graph endpoints in V4L2 Sakari Ailus
2017-07-18 19:03 ` [RFC 08/19] arm: dts: omap3: N9/N950: Add AS3645A camera flash Sakari Ailus
2017-07-18 19:16   ` Sakari Ailus
2017-07-22  9:40   ` Pavel Machek
2017-07-18 19:03 ` [RFC 09/19] v4l2-fwnode: Add conveniences function for parsing generic references Sakari Ailus
2017-07-18 19:03 ` [RFC 10/19] v4l2-fwnode: Add convenience function for parsing common external refs Sakari Ailus
2017-07-18 19:03 ` [RFC 11/19] v4l2-async: Register sub-devices before calling bound callback Sakari Ailus
2017-07-19 11:24   ` Hans Verkuil
2017-07-20 16:09     ` Sakari Ailus
2017-07-20 16:23       ` Hans Verkuil
2017-07-20 19:23         ` Sakari Ailus
2017-07-21  7:14           ` Hans Verkuil
2017-07-20 23:53         ` Kieran Bingham
2017-07-18 19:03 ` [RFC 12/19] v4l2-subdev: Support registering V4L2 sub-device nodes one by one Sakari Ailus
2017-07-18 19:03 ` [RFC 13/19] v4l2-device: Register sub-device nodes at sub-device registration time Sakari Ailus
2017-07-18 19:03 ` [RFC 14/19] omap3isp: Move sub-device link creation to notifier bound callback Sakari Ailus
2017-07-18 19:03 ` [RFC 15/19] omap3isp: Initialise "crashed" media entity enum in probe Sakari Ailus
2017-07-18 19:03 ` [RFC 16/19] omap3isp: Move media device registration to probe Sakari Ailus
2017-07-18 19:03 ` [RFC 17/19] omap3isp: Drop the async notifier callback Sakari Ailus
2017-07-18 19:04 ` [RFC 18/19] v4l2-fwnode: Add abstracted sub-device notifiers Sakari Ailus
2017-07-18 21:19   ` Niklas Söderlund
2017-07-19 22:20     ` Sakari Ailus
2017-07-19 22:33     ` [RFC 1/1] v4l2-subdev: Add a function to set sub-device notifier callbacks Sakari Ailus
2017-07-26 17:48       ` Mauro Carvalho Chehab
2017-07-18 19:04 ` [RFC 19/19] smiapp: Add support for flash and lens devices Sakari Ailus
2017-07-19 11:42 ` [RFC 00/19] Async sub-notifiers and how to use them Hans Verkuil
2017-07-20 16:14   ` Sakari Ailus
2017-07-21  6:57     ` Niklas Söderlund
2017-08-04 18:25       ` Sakari Ailus
2017-08-23  9:09         ` Hans Verkuil
2017-08-23 11:34           ` Pavel Machek [this message]
2017-08-23 12:02             ` Hans Verkuil
2017-08-23 12:29           ` Laurent Pinchart
2017-08-23 15:40             ` Hans Verkuil
2017-08-23 12:59           ` Niklas Söderlund
2017-08-23 13:32             ` Laurent Pinchart
2017-08-23 15:23               ` Hans Verkuil

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