From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.bugwerft.de ([46.23.86.59]:58592 "EHLO mail.bugwerft.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752097AbdKZXuS (ORCPT ); Sun, 26 Nov 2017 18:50:18 -0500 Subject: Re: camss: camera controls missing on vfe interfaces From: Daniel Mack To: Todor Tomov , "laurent.pinchart" , Mauro Carvalho Chehab , Hans Verkuil Cc: linux-media@vger.kernel.org, linux-arm-msm@vger.kernel.org References: <79ac06f5-0c68-14d9-673c-7781881f81b8@zonque.org> <9ac5306d-c048-5d04-4ea9-2d5d08165350@linaro.org> Message-ID: <597a0559-13a1-c3e6-8d03-8dc67c335234@zonque.org> Date: Mon, 27 Nov 2017 00:50:15 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: Hi Todor, everyone, On Monday, November 20, 2017 11:59 AM, Daniel Mack wrote: > On Monday, November 20, 2017 09:32 AM, Todor Tomov wrote: >> It is not a missing feature, it is more of a missing userspace implementation. >> When working with a media oriented device driver, the userspace has to >> config the media pipeline too and if controls are exposed by the subdev nodes, >> the userspace has to configure them on the subdev nodes. >> >> As there weren't a lot of media oriented drivers there is no generic >> implementation/support for this in the userspace (at least I'm not aware of >> any). There have been discussions about adding such functionality in libv4l >> so that applications which do not support media configuration can still >> use these drivers. I'm not sure if decision for this was taken or not or >> is it just that there was noone to actually do the work. Probably Laurent, >> Mauro or Hans know more about what were the plans for this. > > Hmm, that's not good. > > Considering the use-case in our application, the pipeline is set up once > and considered more or less static, and then applications such as the > Chrome browsers make use of the high-level VFE interface. If there are > no controls exposed on that interface, they are not available to the > application. Patching all userspace applications is an uphill battle > that can't be won I'm afraid. > > Is there any good reason not to expose the sensor controls on the VFE? I > guess it would be easy to do, right? Do you see an alternative to implementing the above in order to support existing v4l-enabled applications? Thanks, Daniel