From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from perceval.ideasonboard.com (perceval.ideasonboard.com [213.167.242.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3524B3845A3 for ; Thu, 16 Apr 2026 16:29:25 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.167.242.64 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776356966; cv=none; b=mXB8zVCoPKU3CF/+3FVwFTZ19xE3gOm/L30HJY4QXje8BPs0BO3vFiiVg6Wr9DalqeJiWt/JYJAGX9Fv/39df9KKARWfhzYp7fwuibpqEUaGcHUFYbVk+fswe0oPW8hmCYB+XlLujShlJ2uDbUpOSM61Wg3/I9PjKyOhrLNarrc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1776356966; c=relaxed/simple; bh=jkUYhWqGy/PwbwlHoa6FWaAKNmgyCz2+AcKM+mL1wy0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=EBpWvrUgLlV8/I6qOuXZbEkSrNznp4wUJxGtfFwZAhSLk1FIgHYKa5gWoQqo2J8kTQ3PGIMSliiRSjD2xARALO7KSZ7G5EFIGp/bC/SEOqIPhDW/yR0cdrhsBk5JK4hsq3o5exo38OyGP9tme30kiVgRn+2GyiDLd/KYjxpXFbA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com; spf=pass smtp.mailfrom=ideasonboard.com; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b=MT3yztTM; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="MT3yztTM" Received: from killaraus.ideasonboard.com (2001-14ba-703d-e500--2a1.rev.dnainternet.fi [IPv6:2001:14ba:703d:e500::2a1]) by perceval.ideasonboard.com (Postfix) with UTF8SMTPSA id CCD8E132; Thu, 16 Apr 2026 18:27:47 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1776356868; bh=jkUYhWqGy/PwbwlHoa6FWaAKNmgyCz2+AcKM+mL1wy0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MT3yztTMTXehuGnRG6uGisLIyf4mr5cFM8G7u002plHX1/BJNMZAqrDEgvGIR9vaA 8mv4AjQWcCc6JgRCqws7rMzcwpoURQ/a2LNvEqqwKcr/bTOoydDx8+fooVsGaCTyGv zRP5STys/YXYWsitkdiTKPOXK8nAPdrdSvr0FzIU= Date: Thu, 16 Apr 2026 19:29:20 +0300 From: Laurent Pinchart To: Sakari Ailus Cc: linux-media@vger.kernel.org, hans@jjverkuil.nl, Prabhakar , Kate Hsuan , Dave Stevenson , Tommaso Merciai , Benjamin Mugnier , Sylvain Petinot , Christophe JAILLET , Julien Massot , Naushir Patuck , "Yan, Dongcheng" , "Cao, Bingbu" , "Qiu, Tian Shu" , Stefan Klug , Mirela Rabulea , =?utf-8?B?QW5kcsOp?= Apitzsch , Heimir Thor Sverrisson , Kieran Bingham , Mehdi Djait , Ricardo Ribalda Delgado , Hans de Goede , Jacopo Mondi , Tomi Valkeinen , David Plowman , "Yu, Ong Hock" , "Ng, Khai Wen" , Jai Luthra , Rishikesh Donadkar Subject: Re: [PATCH v4 22/29] media: mc: Add MEDIA_LNK_FL_VALIDATE_LATE Message-ID: <20260416162920.GF1823068@killaraus.ideasonboard.com> References: <20260408153939.969381-1-sakari.ailus@linux.intel.com> <20260408153939.969381-23-sakari.ailus@linux.intel.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260408153939.969381-23-sakari.ailus@linux.intel.com> On Wed, Apr 08, 2026 at 06:39:31PM +0300, Sakari Ailus wrote: > Add MEDIA_LNK_FL_VALIDATE_LATE flag to support late validation of links. > This is serving the use case where video devices are configured and > started streaming indepenently of each other but this sequence may be run > in series, in such a way that a video device in a pipeline starts > streaming before another one is configured. > > Before this flag, drivers have resorted to implementing the link > validation separately for the video nodes as part of streaming start > sequence. > > media_pipeline_start() shall be called on each leaf entity connected to > the graph with a link where MEDIA_LNK_FL_VALIDATE_LATE is set before > uphardware operation. I don't like this much, especially given that there are no users in this series, so I can't check how it's used. Let's postpone it. > Signed-off-by: Sakari Ailus > --- > .../media/mediactl/media-ioc-setup-link.rst | 4 + > .../media/mediactl/media-types.rst | 5 ++ > drivers/media/mc/mc-entity.c | 82 ++++++++++++++++++- > include/uapi/linux/media.h | 1 + > 4 files changed, 88 insertions(+), 4 deletions(-) > > diff --git a/Documentation/userspace-api/media/mediactl/media-ioc-setup-link.rst b/Documentation/userspace-api/media/mediactl/media-ioc-setup-link.rst > index 23208300cb61..7c2bced57e77 100644 > --- a/Documentation/userspace-api/media/mediactl/media-ioc-setup-link.rst > +++ b/Documentation/userspace-api/media/mediactl/media-ioc-setup-link.rst > @@ -49,6 +49,10 @@ Only links marked with the ``DYNAMIC`` link flag can be enabled/disabled > while streaming media data. Attempting to enable or disable a streaming > non-dynamic link will return an ``EBUSY`` error code. > > +Pipeline validation may be delayed for links marked with the ``VALIDATE_LATE`` > +flag until actual hardware operation even if the rest of the pipeline would be > +validated at an earlier point of time. > + > If the specified link can't be found the driver returns with an ``EINVAL`` > error code. > > diff --git a/Documentation/userspace-api/media/mediactl/media-types.rst b/Documentation/userspace-api/media/mediactl/media-types.rst > index 6332e8395263..d6a690655a01 100644 > --- a/Documentation/userspace-api/media/mediactl/media-types.rst > +++ b/Documentation/userspace-api/media/mediactl/media-types.rst > @@ -391,6 +391,7 @@ must be set for every pad. > .. _MEDIA-LNK-FL-ENABLED: > .. _MEDIA-LNK-FL-IMMUTABLE: > .. _MEDIA-LNK-FL-DYNAMIC: > +.. _MEDIA-LNK-FL-VALIDATE-LATE: > .. _MEDIA-LNK-FL-LINK-TYPE: > > .. flat-table:: Media link flags > @@ -410,6 +411,10 @@ must be set for every pad. > - The link enabled state can be modified during streaming. This flag > is set by drivers and is read-only for applications. > > + * - ``MEDIA_LNK_FL_VALIDATE_LATE`` > + - The validation of the link may be delayed up to until the start of > + hardware operation. > + > * - ``MEDIA_LNK_FL_LINK_TYPE`` > - This is a bitmask that defines the type of the link. The following > link types are currently supported: > diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c > index 287eded356bb..5b0162f81425 100644 > --- a/drivers/media/mc/mc-entity.c > +++ b/drivers/media/mc/mc-entity.c > @@ -771,7 +771,7 @@ static int media_pipeline_populate(struct media_pipeline *pipe, > static int > __media_pipeline_validate_one(struct media_pad *origin, > struct media_pad *pad, struct media_link *link, > - bool *has_enabled_link) > + bool *has_enabled_link, bool skip_validation) > { > struct media_device *mdev = origin->graph_obj.mdev; > struct media_entity *entity = pad->entity; > @@ -784,6 +784,9 @@ __media_pipeline_validate_one(struct media_pad *origin, > if (has_enabled_link) > *has_enabled_link = true; > > + if (skip_validation) > + return 0; > + > /* Skip validation if the current pad isn't the sink pad of the link. */ > if (link->sink != pad) > return 0; > @@ -825,11 +828,48 @@ __must_check int __media_pipeline_start(struct media_pad *origin, > return -EINVAL; > > /* > - * If the pipeline has already been started, it is guaranteed to be > - * valid, so just increase the start count. > + * Increase start count on pipelines that have been validated > + * earlier. Also check links with the VALIDATE_LATE flag here. > */ > if (pipe->start_count) { > + struct media_link *link; > + > + link = __media_entity_next_link(origin->entity, NULL, > + MEDIA_LNK_FL_DATA_LINK); > + if (link && link->flags & MEDIA_LNK_FL_VALIDATE_LATE) { > + struct media_link *link2 = > + __media_entity_next_link(origin->entity, link, > + MEDIA_LNK_FL_DATA_LINK); > + bool has_enabled_link = false; > + > + /* > + * Only a single pad is allowed for VALIDATE_LATE > + * links. That pad needs to have exactly one link. > + */ > + if (origin->entity->num_pads != 1) > + return -EINVAL; > + > + if (!link || link2) > + return -EINVAL; > + > + dev_dbg(mdev->dev, > + "Validating pad '%s':%u late\n", > + origin->entity->name, origin->index); > + > + ret = __media_pipeline_validate_one(link->sink, > + link->sink, link, > + &has_enabled_link, > + false); > + if (ret) > + return ret; > + > + if (origin->flags & MEDIA_PAD_FL_MUST_CONNECT && > + !has_enabled_link) > + return -ENOLINK; > + } > + > pipe->start_count++; > + > return 0; > } > > @@ -873,12 +913,19 @@ __must_check int __media_pipeline_start(struct media_pad *origin, > * the connected sink pad to avoid duplicating checks. > */ > for_each_media_entity_data_link(entity, link) { > + /* Skip late-validated links not connected to origin. */ > + bool skip_validation = > + link->flags & MEDIA_LNK_FL_VALIDATE_LATE && > + link->sink != origin && > + link->source != origin; > + > /* Skip links unrelated to the current pad. */ > if (link->sink != pad && link->source != pad) > continue; > > ret = __media_pipeline_validate_one(origin, pad, link, > - &has_enabled_link); > + &has_enabled_link, > + skip_validation); > if (ret) > goto error; > } > @@ -1158,6 +1205,33 @@ media_create_pad_link(struct media_entity *source, u16 source_pad, > if (WARN_ON(!(sink->pads[sink_pad].flags & MEDIA_PAD_FL_SINK))) > return -EINVAL; > > + /* > + * With the late validate flag, either source or sink shall have exactly > + * one pad and no links before this one. Similarly, no links may be > + * added to entities with a single pad and an existing late-validated > + * link. > + */ > + if (flags & MEDIA_LNK_FL_VALIDATE_LATE) { > + if (!(source->num_pads == 1 && !source->num_links) && > + !(sink->num_pads == 1 && !sink->num_links)) > + return -EINVAL; > + } else { > + struct media_entity *entities[] = { source, sink }; > + > + for (unsigned int i = 0; i < ARRAY_SIZE(entities); i++) { > + if (entities[i]->num_pads != 1) > + continue; > + > + struct media_link *__link = > + __media_entity_next_link(entities[i], NULL, > + MEDIA_LNK_FL_DATA_LINK); > + > + if (__link && > + __link->flags & MEDIA_LNK_FL_VALIDATE_LATE) > + return -EINVAL; > + } > + } > + > link = media_add_link(&source->links); > if (link == NULL) > return -ENOMEM; > diff --git a/include/uapi/linux/media.h b/include/uapi/linux/media.h > index 1c80b1d6bbaf..c96e2118ea99 100644 > --- a/include/uapi/linux/media.h > +++ b/include/uapi/linux/media.h > @@ -219,6 +219,7 @@ struct media_pad_desc { > #define MEDIA_LNK_FL_ENABLED (1U << 0) > #define MEDIA_LNK_FL_IMMUTABLE (1U << 1) > #define MEDIA_LNK_FL_DYNAMIC (1U << 2) > +#define MEDIA_LNK_FL_VALIDATE_LATE (1U << 3) > > #define MEDIA_LNK_FL_LINK_TYPE (0xf << 28) > # define MEDIA_LNK_FL_DATA_LINK (0U << 28) -- Regards, Laurent Pinchart