From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from bombadil.infradead.org ([198.137.202.133]:35662 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752260AbeF2M3B (ORCPT ); Fri, 29 Jun 2018 08:29:01 -0400 Date: Fri, 29 Jun 2018 09:28:56 -0300 From: Mauro Carvalho Chehab To: Hans Verkuil Cc: Niklas =?UTF-8?B?U8O2ZGVybHVuZA==?= , linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org Subject: Re: [PATCH v2 2/2] v4l: Add support for STD ioctls on subdev nodes Message-ID: <20180629092856.73406202@coco.lan> In-Reply-To: <1b948535-8067-fef6-efd9-92aff3049ec5@xs4all.nl> References: <20180517143016.13501-1-niklas.soderlund+renesas@ragnatech.se> <20180517143016.13501-3-niklas.soderlund+renesas@ragnatech.se> <20180628083732.3679d730@coco.lan> <536a05bd-372e-a509-a6b6-0a3e916e48ae@xs4all.nl> <20180629070647.1ce7f73b@coco.lan> <1b948535-8067-fef6-efd9-92aff3049ec5@xs4all.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: linux-media-owner@vger.kernel.org List-ID: Em Fri, 29 Jun 2018 12:26:20 +0200 Hans Verkuil escreveu: > On 06/29/18 12:06, Mauro Carvalho Chehab wrote: > > Em Thu, 28 Jun 2018 14:47:05 +0200 > > Hans Verkuil escreveu: > > =20 > >> On 06/28/18 13:37, Mauro Carvalho Chehab wrote: =20 > >>> Em Thu, 17 May 2018 16:30:16 +0200 > >>> Niklas S=C3=B6derlund = escreveu: > >>> =20 > >>>> There is no way to control the standard of subdevices which are part= of > >>>> a media device. The ioctls which exists all target video devices > >>>> explicitly and the idea is that the video device should talk to the > >>>> subdevice. For subdevices part of a media graph this is not possible= and > >>>> the standard must be controlled on the subdev device directly. =20 > >>> > >>> Why isn't it possible? A media pipeline should have at least a video > >>> devnode where the standard ioctls will be issued. =20 > >> > >> Not for an MC-centric device like the r-car or imx. It's why we have v= 4l-subdev > >> ioctls for the DV_TIMINGS API, but the corresponding SDTV standards AP= I is > >> missing. > >> > >> And in a complex scenario there is nothing preventing you from having = multiple > >> SDTV inputs, some of which need PAL-BG, some SECAM, some NTSC (less li= kely) > >> which are all composed together (think security cameras or something l= ike that). > >> > >> You definitely cannot set the standard from a video device. If nothing= else, > >> it would be completely inconsistent with how HDMI inputs work. > >> > >> The whole point of MC centric devices is that you *don't* control subd= evs > >> from video nodes. =20 > >=20 > > Well, the way it is, this change is disruptive, as, as far as I remembe= r, > > MC-based devices with tvp5150 already sets STD via the /dev/video devic= e. =20 >=20 > Really? Which driver? I am not aware of this and I think you are mistaken. > Remember that we are talking about MC-centric drivers. em28xx is not MC-c= entric, > even though it has a media device. OMAP3. There are some boards out there with tvp5150. >=20 > >=20 > > If we're willing to add it, we'll need to be clear when one approach > > should be taken, and be clear that, if the SUBDEV version is used, the > > driver should not support the non-subdev option. =20 >=20 > Of course, but in the case of em28xx the tvp5150 v4l-subdev node is never > created, so this is not a problem. >=20 > Regards, >=20 > Hans >=20 > > =20 > >> > >> Regards, > >> > >> Hans > >> =20 > >>> So, I don't see why you would need to explicitly set the standard ins= ide > >>> a sub-device. > >>> > >>> The way I see, inside a given pipeline, all subdevs should be using t= he > >>> same video standard (maybe except for a m2m device with would have so= me > >>> coded that would be doing format conversion). > >>> > >>> Am I missing something? > >>> > >>> Thanks, > >>> Mauro > >>> =20 > >> =20 > >=20 > >=20 > >=20 > > Thanks, > > Mauro > > =20 >=20 Thanks, Mauro