From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933092AbaLAX0E (ORCPT ); Mon, 1 Dec 2014 18:26:04 -0500 Received: from galahad.ideasonboard.com ([185.26.127.97]:59946 "EHLO galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932484AbaLAXZs (ORCPT ); Mon, 1 Dec 2014 18:25:48 -0500 From: Laurent Pinchart To: Prabhakar Lad Cc: Hans Verkuil , linux-media , Hans Verkuil , Sakari Ailus , LKML , Sakari Ailus Subject: Re: [PATCH] media: v4l2-subdev.h: drop the guard CONFIG_VIDEO_V4L2_SUBDEV_API for v4l2_subdev_get_try_*() Date: Tue, 02 Dec 2014 01:26:21 +0200 Message-ID: <1429705.acTXlHE2TG@avalon> User-Agent: KMail/4.12.5 (Linux/3.16.5-gentoo; KDE/4.12.5; x86_64; ; ) In-Reply-To: References: <1416220913-5047-1-git-send-email-prabhakar.csengg@gmail.com> <1680188.7K1XCBdsCk@avalon> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Prabhakar, On Sunday 30 November 2014 21:30:35 Prabhakar Lad wrote: > On Sun, Nov 30, 2014 at 9:16 PM, Laurent Pinchart wrote: > > On Sunday 30 November 2014 21:05:50 Prabhakar Lad wrote: > >> On Sat, Nov 29, 2014 at 7:12 PM, Laurent Pinchart wrote: > >> > Hi Prabhakar, > >> > >> [Snip] > >> > >>>>> Sure. That's a better choice than removing the config option > >>>>> dependency of the fields struct v4l2_subdev. > >>> > >>> Decoupling CONFIG_VIDEO_V4L2_SUBDEV_API from the availability of the > >>> in-kernel pad format and selection rectangles helpers is definitely a > >>> good idea. I was thinking about decoupling the try format and > >>> rectangles from v4l2_subdev_fh by creating a kind of configuration store > >>> structure to store them, and embedding that structure in v4l2_subdev_fh. > >>> The pad-level operations would then take a pointer to the configuration > >>> store instead of the v4l2_subdev_fh. Bridge drivers that want to > >>> implement TRY_FMT based on pad-level operations would create a > >>> configuration store, use the pad-level operations, and destroy the > >>> configuration store. The userspace subdev API would use the > >>> configuration store from the file handle. > >> > >> are planning to work/post any time soon ? Or are you OK with suggestion > >> from Hans ? > > > > I have no plan to work on that myself now, I was hoping you could > > implement it ;-) > > OK will implement it. > > Can you please elaborate a more on this "The userspace subdev API would use > the configuration store from the file handle." Basically, 1. Create a subdev pad configuration store structure to store the formats and selection rectangles for each pad. 2. Embed an instance of that structure in v4l2_subdev_fh. 3. Modify the subdev pad ops to take a configuration store pointer instead of a file handle pointer. The userspace API implementation (v4l2-subdev.c) would then pass &fh->store to the pad operations instead of fh. Bridge drivers that need to implement TRY_FMT on top of pad ops would create a temporary store (or temporary stores when multiple subsdevs are involved), call the pad ops with a pointer to the temporary store to propagate TRY formats, destroy the store(s) and return the resulting format. Is that clear ? -- Regards, Laurent Pinchart