From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from perceval.ideasonboard.com ([95.142.166.194]:44552 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751124AbaCFKfx (ORCPT ); Thu, 6 Mar 2014 05:35:53 -0500 From: Laurent Pinchart To: Hans Verkuil Cc: linux-media@vger.kernel.org, marbugge@cisco.com Subject: Re: [RFCv1 PATCH 0/4] add G/S_EDID support for video nodes Date: Thu, 06 Mar 2014 11:37:22 +0100 Message-ID: <2719510.vO5HGhFCIt@avalon> In-Reply-To: <5318252B.2080802@xs4all.nl> References: <1393932659-13817-1-git-send-email-hverkuil@xs4all.nl> <2313806.6Mf9nE69NY@avalon> <5318252B.2080802@xs4all.nl> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-media-owner@vger.kernel.org List-ID: Hi Hans, On Thursday 06 March 2014 08:35:07 Hans Verkuil wrote: > On 03/06/2014 02:45 AM, Laurent Pinchart wrote: > > On Tuesday 04 March 2014 12:30:55 Hans Verkuil wrote: > >> Currently the VIDIOC_SUBDEV_G/S_EDID and struct v4l2_subdev_edid are > >> subdev APIs. However, that's in reality quite annoying since for simple > >> video pipelines there is no need to create v4l-subdev device nodes for > >> anything else except for setting or getting EDIDs. > >> > >> What happens in practice is that v4l2 bridge drivers add explicit support > >> for VIDIOC_SUBDEV_G/S_EDID themselves, just to avoid having to create > >> subdev device nodes just for this. > >> > >> So this patch series makes the ioctls available as regular ioctls as > >> well. In that case the pad field should be set to 0 and the bridge driver > >> will fill in the right pad value internally depending on the current > >> input or output and pass it along to the actual subdev driver. > > > > Would it make sense to allow usage of the pad field on video nodes as well > > ? > No, really not. The video node driver has full control over which > inputs/outputs map to which pads. None of that is (or should be) visible > from userspace. What about using the pad field as an input number in that case ? That would allow getting and setting EDID for the different inputs without requiring to change the active input, just like we can do with the subdev API. > What should probably change is that rather than requiring userspace to set > pad to 0, I just say that it is ignored. The bridge driver will fill in the > pad before handing it over to the relevant subdev. Requiring apps to set it > to 0 (which is a valid pad number anyway, so that doesn't really help with > possible future use of the field) will require the driver to set it to 0 as > well after having called the subdev. Which is annoying and will be > forgotten anyway. > > I also need to mention in the docbook that if it is called for a pad, an > input or an output that does not support EDIDs these ioctls will return > -EINVAL. > > I'll post a REVIEWv1 series soon. > > Regards, > > Hans > > > Apart from that and minor issues with patch 2/4 this series looks good to > > me. -- Regards, Laurent Pinchart