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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4EDD6C433EF for ; Mon, 20 Dec 2021 12:51:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231709AbhLTMvg (ORCPT ); Mon, 20 Dec 2021 07:51:36 -0500 Received: from mga01.intel.com ([192.55.52.88]:63637 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230262AbhLTMvg (ORCPT ); Mon, 20 Dec 2021 07:51:36 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10203"; a="264341006" X-IronPort-AV: E=Sophos;i="5.88,220,1635231600"; d="scan'208";a="264341006" Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Dec 2021 04:51:36 -0800 X-IronPort-AV: E=Sophos;i="5.88,220,1635231600"; d="scan'208";a="586305577" Received: from paasikivi.fi.intel.com ([10.237.72.42]) by fmsmga004-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 20 Dec 2021 04:51:34 -0800 Received: from paasikivi.fi.intel.com (localhost [127.0.0.1]) by paasikivi.fi.intel.com (Postfix) with SMTP id 14178201D7; Mon, 20 Dec 2021 14:51:32 +0200 (EET) Date: Mon, 20 Dec 2021 14:51:32 +0200 From: Sakari Ailus To: Tomi Valkeinen Cc: linux-media@vger.kernel.org, Jacopo Mondi , Laurent Pinchart , niklas.soderlund+renesas@ragnatech.se, Mauro Carvalho Chehab , Hans Verkuil , Pratyush Yadav Subject: Re: [PATCH v2 5/6] media: subdev: Add v4l2_subdev_lock_and_return_state() Message-ID: References: <20211217135022.364954-1-tomi.valkeinen@ideasonboard.com> <20211217135022.364954-6-tomi.valkeinen@ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211217135022.364954-6-tomi.valkeinen@ideasonboard.com> Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Moi, On Fri, Dec 17, 2021 at 03:50:21PM +0200, Tomi Valkeinen wrote: > All suitable subdev ops are now passed either the TRY or the ACTIVE > state by the v4l2 core. However, other subdev drivers can still call the > ops passing NULL as the state, implying the active case. > > For all current upstream drivers this doesn't matter, as they do not > expect to get a valid state for ACTIVE case. But future drivers which > support multiplexed streaming and routing will depend on getting a state > for both active and try cases. > > For new drivers we can mandate that the pipelines where the drivers are > used need to pass the state properly, or preferably, not call such > subdev ops at all. > > However, if an existing subdev driver is changed to support multiplexed > streams, the driver has to consider cases where its ops will be called > with NULL state. The problem can easily be solved by using the > v4l2_subdev_lock_and_return_state() helper, introduced here. > > Signed-off-by: Tomi Valkeinen > Reviewed-by: Laurent Pinchart > Reviewed-by: Hans Verkuil > Reviewed-by: Jacopo Mondi > --- > include/media/v4l2-subdev.h | 36 ++++++++++++++++++++++++++++++++++++ > 1 file changed, 36 insertions(+) > > diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h > index 867e19ef80bd..d6c7db1d37e4 100644 > --- a/include/media/v4l2-subdev.h > +++ b/include/media/v4l2-subdev.h > @@ -1321,4 +1321,40 @@ void v4l2_subdev_lock_state(struct v4l2_subdev_state *state); > */ > void v4l2_subdev_unlock_state(struct v4l2_subdev_state *state); > > +/** > + * v4l2_subdev_lock_and_return_state() - Gets locked try or active subdev state > + * @sd: subdevice > + * @state: subdevice state as passed to the subdev op > + * > + * Due to legacy reasons, when subdev drivers call ops in other subdevs they use > + * NULL as the state parameter, as subdevs always used to have their active > + * state stored privately. > + * > + * However, newer state-aware subdev drivers, which store their active state in > + * a common place, subdev->active_state, expect to always get a proper state as > + * a parameter. > + * > + * These state-aware drivers can use v4l2_subdev_lock_and_return_state() instead > + * of v4l2_subdev_lock_state(). v4l2_subdev_lock_and_return_state() solves the > + * issue by using subdev->active_state in case the passed state is NULL. > + * > + * This is a temporary helper function, and should be removed when we can ensure > + * that all drivers pass proper state when calling other subdevs. > + */ > +static inline struct v4l2_subdev_state * > +v4l2_subdev_lock_and_return_state(struct v4l2_subdev *sd, > + struct v4l2_subdev_state *state) > +{ > + if (!state) > + dev_notice_once(sd->dev, I thought about this a little more. This currently warns once when there's something that calls the function with NULL state. How about going a bit further, moving this to a macro so all instances will be covered, and then using WARN_ON_ONCE() so there would be a clear indication where the warning comes from? > + "The provided state is NULL. Adjusting to the subdev active state.\n" > + "Please consider porting your driver to the new state management API.\n"); > + > + state = state ? state : sd->active_state; > + > + v4l2_subdev_lock_state(state); > + > + return state; > +} > + > #endif -- Kind regards. Sakari Ailus