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 C9126C433F5 for ; Fri, 17 Dec 2021 17:54:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239964AbhLQRyn (ORCPT ); Fri, 17 Dec 2021 12:54:43 -0500 Received: from perceval.ideasonboard.com ([213.167.242.64]:57724 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239961AbhLQRym (ORCPT ); Fri, 17 Dec 2021 12:54:42 -0500 Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 9F57D93; Fri, 17 Dec 2021 18:54:40 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1639763680; bh=BaokllrVKanSbefKvctTebuB7/MixIU763lM1tb6MAk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=ahVQzAFGPzQF1IoYwetati/c22ftTHDNWJX0uERgJn4TYmJtb5iewyxDZSlYShoHE FTuAVsO8FxB5NaM92p/mMYaJ3dgJv/oIv6He7cDg+5DIn/2+v/u3pIBoulL8xEC6BB Pe5GPyKWOimWbjR7++Ov/rs7DGQjkJzhXLzrrLko= Date: Fri, 17 Dec 2021 19:54:38 +0200 From: Laurent Pinchart To: Sakari Ailus 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=utf-8 Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org Hi Sakari, On Fri, Dec 17, 2021 at 07:43:55PM +0200, Sakari Ailus wrote: > On Thu, Dec 16, 2021 at 04:34:22PM +0200, Laurent Pinchart wrote: > > 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. The goal is to notice the issue, to get it fixed, so I'd prefer a few warnings instead of a dev_warn_once(). Please note that the first 6 patches from this series have been posted in a new version as "[PATCH v2 0/6] v4l: subdev active state" (20211217135022.364954-1-tomi.valkeinen@ideasonboard.com). > > Reviewed-by: Laurent Pinchart > > > > > + > > > + v4l2_subdev_lock_state(state); > > > + > > > + return state; > > > +} > > > + > > > #endif -- Regards, Laurent Pinchart