From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2067CC43382 for ; Thu, 27 Sep 2018 09:52:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B6F5121582 for ; Thu, 27 Sep 2018 09:52:40 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B6F5121582 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=xs4all.nl Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727262AbeI0QKG (ORCPT ); Thu, 27 Sep 2018 12:10:06 -0400 Received: from lb3-smtp-cloud8.xs4all.net ([194.109.24.29]:39482 "EHLO lb3-smtp-cloud8.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727018AbeI0QKF (ORCPT ); Thu, 27 Sep 2018 12:10:05 -0400 Received: from [192.168.1.10] ([80.101.105.217]) by smtp-cloud8.xs4all.net with ESMTPA id 5SyJgvC5DgyCD5SyKgUmn0; Thu, 27 Sep 2018 11:52:37 +0200 Subject: Re: [PATCH 0/2] media: intel-ipu3: allow the media graph to be used even if a subdev fails To: Javier Martinez Canillas , linux-kernel@vger.kernel.org Cc: Tian Shu Qiu , Sakari Ailus , Mauro Carvalho Chehab , Jian Xu Zheng , Yong Zhi , Bingbu Cao , linux-media@vger.kernel.org References: <20180904113018.14428-1-javierm@redhat.com> From: Hans Verkuil Message-ID: <0e31ae40-276e-22be-c6aa-b62f8dbea79e@xs4all.nl> Date: Thu, 27 Sep 2018 11:52:35 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20180904113018.14428-1-javierm@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-CMAE-Envelope: MS4wfCg7rBr719AgtAd1kBnW9vWrh4/OBHXY5KotqAcEwE62k9xHcJsuCV6v8EzvL/F047s0jvgeMYCtmnWl4i8MKKin1nhBBbjy2b8wx7uRlYZSfjecsDLj 0dHqaOX3ry33Pm0vJEwsGYNwPOleE2I0IlTRkCYZfOLJbnUgnUY9NrLV5QBpdARf88YjfThF4u4UHSE+kZeEkx0AVGkNJfM2/rsRSh53PrFw1jxKj7YHJX+k E7jjINUGMBIOCxLOcN6o2A4aZnNLuqbqfLE2OrFm4GXrcXl6iMLRmDAowsMrpKLG1nx3TRVJM4tIMtcylF3dvvIhZwMxtsoxHbi4BvYwhznWYmWcn9iQSDrY 37CMQChRcr3IgpXm2e/Tvo/480/GZRMB0+Gsqu9MzugzvGXNRymH+ZSn4ICd8r/vGpulWWN9YoMACyvX7EJCVSVJbtbI5vTWg2EnK+PBPdYUlHaBD9M= Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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(-) >