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 BF3BBC433EF for ; Fri, 17 Dec 2021 17:44:01 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236274AbhLQRoB (ORCPT ); Fri, 17 Dec 2021 12:44:01 -0500 Received: from mga01.intel.com ([192.55.52.88]:3059 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236112AbhLQRoA (ORCPT ); Fri, 17 Dec 2021 12:44:00 -0500 X-IronPort-AV: E=McAfee;i="6200,9189,10201"; a="263976126" X-IronPort-AV: E=Sophos;i="5.88,214,1635231600"; d="scan'208";a="263976126" Received: from orsmga001.jf.intel.com ([10.7.209.18]) by fmsmga101.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Dec 2021 09:44:00 -0800 X-IronPort-AV: E=Sophos;i="5.88,214,1635231600"; d="scan'208";a="546462941" Received: from paasikivi.fi.intel.com ([10.237.72.42]) by orsmga001-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Dec 2021 09:43:57 -0800 Received: from paasikivi.fi.intel.com (localhost [127.0.0.1]) by paasikivi.fi.intel.com (Postfix) with SMTP id 9CBC720531; Fri, 17 Dec 2021 19:43:55 +0200 (EET) Date: Fri, 17 Dec 2021 19:43:55 +0200 From: Sakari Ailus To: Laurent Pinchart Cc: Tomi Valkeinen , linux-media@vger.kernel.org, Jacopo Mondi , niklas.soderlund+renesas@ragnatech.se, Mauro Carvalho Chehab , Hans Verkuil , Pratyush Yadav Subject: Re: [PATCH v10 05/38] media: subdev: Add v4l2_subdev_lock_and_return_state() Message-ID: References: <20211130141536.891878-1-tomi.valkeinen@ideasonboard.com> <20211130141536.891878-6-tomi.valkeinen@ideasonboard.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Laurent, On Thu, Dec 16, 2021 at 04:34:22PM +0200, Laurent Pinchart wrote: > Hi Tomi, > > Thank you for the patch. > > On Tue, Nov 30, 2021 at 04:15:03PM +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 > > --- > > include/media/v4l2-subdev.h | 31 +++++++++++++++++++++++++++++++ > > 1 file changed, 31 insertions(+) > > > > diff --git a/include/media/v4l2-subdev.h b/include/media/v4l2-subdev.h > > index 1810dde9c7fc..873bbe0686e3 100644 > > --- a/include/media/v4l2-subdev.h > > +++ b/include/media/v4l2-subdev.h > > @@ -1317,4 +1317,35 @@ 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->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) > > +{ > > + state = state ? state : sd->active_state; > > Can we add a dev_warn() when state is NULL ? This will help speeding up > the transition. Wouldn't this produce lots of warnings? I'd rather use dev_warn_once() to avoid flooding logs. > > Reviewed-by: Laurent Pinchart > > > + > > + v4l2_subdev_lock_state(state); > > + > > + return state; > > +} > > + > > #endif > -- Sakari Ailus