linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Hans Verkuil <hverkuil@xs4all.nl>
To: Javier Martinez Canillas <javierm@redhat.com>,
	linux-kernel@vger.kernel.org
Cc: Tian Shu Qiu <tian.shu.qiu@intel.com>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Mauro Carvalho Chehab <mchehab@kernel.org>,
	Jian Xu Zheng <jian.xu.zheng@intel.com>,
	Yong Zhi <yong.zhi@intel.com>, Bingbu Cao <bingbu.cao@intel.com>,
	linux-media@vger.kernel.org
Subject: Re: [PATCH 0/2] media: intel-ipu3: allow the media graph to be used even if a subdev fails
Date: Thu, 27 Sep 2018 11:52:35 +0200	[thread overview]
Message-ID: <0e31ae40-276e-22be-c6aa-b62f8dbea79e@xs4all.nl> (raw)
In-Reply-To: <20180904113018.14428-1-javierm@redhat.com>

Hi Javier,

On 09/04/2018 01:30 PM, Javier Martinez Canillas wrote:
> Hello,
> 
> This series allows the ipu3-cio2 driver to properly expose a subset of the
> media graph even if some drivers for the pending subdevices fail to probe.
> 
> Currently the driver exposes a non-functional graph since the pad links are
> created and the subdev dev nodes are registered in the v4l2 async .complete
> callback. Instead, these operations should be done in the .bound callback.
> 
> Patch #1 just adds a v4l2_device_register_subdev_node() function to allow
> registering a single device node for a subdev of a v4l2 device.
> 
> Patch #2 moves the logic of the ipu3-cio2 .complete callback to the .bound
> callback. The .complete callback is just removed since is empy after that.

Sorry, I missed this series until you pointed to it on irc just now :-)

I have discussed this topic before with Sakari and Laurent. My main problem
with this is how an application can discover that not everything is online?
And which parts are offline?

Perhaps a car with 10 cameras can function with 9, but not with 8. How would
userspace know?

I completely agree that we need to support these advanced scenarios (including
what happens when a camera suddenly fails), but it is the userspace aspects
for which I would like to see an RFC first before you can do these things.

Regards,

	Hans

> 
> Best regards,
> Javier
> 
> 
> Javier Martinez Canillas (2):
>   [media] v4l: allow to register dev nodes for individual v4l2 subdevs
>   media: intel-ipu3: create pad links and register subdev nodes at bound
>     time
> 
>  drivers/media/pci/intel/ipu3/ipu3-cio2.c | 66 ++++++-----------
>  drivers/media/v4l2-core/v4l2-device.c    | 90 ++++++++++++++----------
>  include/media/v4l2-device.h              | 10 +++
>  3 files changed, 85 insertions(+), 81 deletions(-)
> 


  parent reply	other threads:[~2018-09-27  9:52 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-09-04 11:30 [PATCH 0/2] media: intel-ipu3: allow the media graph to be used even if a subdev fails Javier Martinez Canillas
2018-09-04 11:30 ` [PATCH 1/2] [media] v4l: allow to register dev nodes for individual v4l2 subdevs Javier Martinez Canillas
2018-09-17 16:46   ` Sakari Ailus
2018-09-17 17:13     ` Javier Martinez Canillas
2018-09-04 11:30 ` [PATCH 2/2] media: intel-ipu3: create pad links and register subdev nodes at bound time Javier Martinez Canillas
2018-09-17 16:21 ` [PATCH 0/2] media: intel-ipu3: allow the media graph to be used even if a subdev fails Javier Martinez Canillas
2018-09-27  9:52 ` Hans Verkuil [this message]
2018-09-27 10:13   ` Mauro Carvalho Chehab
2018-09-27 10:22     ` Hans Verkuil
2018-11-14  8:28       ` Tomasz Figa

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=0e31ae40-276e-22be-c6aa-b62f8dbea79e@xs4all.nl \
    --to=hverkuil@xs4all.nl \
    --cc=bingbu.cao@intel.com \
    --cc=javierm@redhat.com \
    --cc=jian.xu.zheng@intel.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-media@vger.kernel.org \
    --cc=mchehab@kernel.org \
    --cc=sakari.ailus@linux.intel.com \
    --cc=tian.shu.qiu@intel.com \
    --cc=yong.zhi@intel.com \
    /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).