From patchwork Thu Jan 13 15:00:42 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Laurent Pinchart X-Patchwork-Id: 12712850 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 642FDC4321E for ; Thu, 13 Jan 2022 15:01:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235913AbiAMPBB (ORCPT ); Thu, 13 Jan 2022 10:01:01 -0500 Received: from perceval.ideasonboard.com ([213.167.242.64]:42104 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233641AbiAMPBA (ORCPT ); Thu, 13 Jan 2022 10:01:00 -0500 Received: from pendragon.lan (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 1E5ABE81; Thu, 13 Jan 2022 16:00:59 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1642086059; bh=I4B4eDk1TbuJnwrMhQfHOYenxD6XdfiTPCciEvfpguI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GbkMU+DcVllLZcEN66xdZ4CbmVqo7qOUecz+B2AzX3mlJdUWqZ8B4wjdTKa+nNGUq usr3y+VkcDLXw+CmbDuCyy3Hd5b7JgajPrZ6QuTbzIPj4jCKnaxoDtfuJDCc3zJV6u vZ+9/4yUm+zQpStqp0JHcgva3FYLVXIb6rEDDXxY= From: Laurent Pinchart To: linux-media@vger.kernel.org Cc: linux-renesas-soc@vger.kernel.org, Sakari Ailus , =?utf-8?q?Niklas_S=C3=B6derlund?= , Tomi Valkeinen , Jacopo Mondi , Laurent Pinchart Subject: [PATCH 2/2] media: media-entity: Simplify media_pipeline_start() Date: Thu, 13 Jan 2022 17:00:42 +0200 Message-Id: <20220113150042.15630-3-laurent.pinchart+renesas@ideasonboard.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220113150042.15630-1-laurent.pinchart+renesas@ideasonboard.com> References: <20220113150042.15630-1-laurent.pinchart+renesas@ideasonboard.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org From: Laurent Pinchart The media_pipeline_start() function has two purposes: it constructs a pipeline by recording the entities that are part of it, gathered from a graph walk, and validate the media links. The pipeline pointer is stored in the media_entity structure as part of this process, and the entity's stream count is increased, to record that the entity is streaming. When multiple video nodes are present in a pipeline, media_pipeline_start() is typically called on all of them, with the same pipeline pointer. This is taken into account in media_pipeline_start() by skipping validation for entities that are already part of the pipeline, while returning an error if an entity is part of a different pipeline. It turns out that this process is overly complicated. When media_pipeline_start() is called for the first time, it constructs the full pipeline, adding all entities and validating all the links. Subsequent calls to media_pipeline_start() are then nearly no-ops, they only increase the stream count on the pipeline and on all entities. The media_entity stream_count field is used for two purposes: checking if the entity is streaming, and detecting when a call to media_pipeline_stop() balances needs to reset the entity pipe pointer to NULL. The former can easily be replaced by a check of the pipe pointer. Simplify media_pipeline_start() by avoiding the pipeline walk on all calls but the first one, and drop the media_entity stream_count field. media_pipeline_stop() is updated accordingly. Signed-off-by: Laurent Pinchart --- drivers/media/mc/mc-entity.c | 52 +++++++++++++++--------------------- include/media/media-entity.h | 11 +++----- 2 files changed, 26 insertions(+), 37 deletions(-) diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c index f83e043f0f3b..8ab0913d8d82 100644 --- a/drivers/media/mc/mc-entity.c +++ b/drivers/media/mc/mc-entity.c @@ -396,20 +396,21 @@ __must_check int __media_pipeline_start(struct media_entity *entity, struct media_link *link; int ret; - if (!pipe->streaming_count++) { - ret = media_graph_walk_init(&pipe->graph, mdev); - if (ret) - goto error_graph_walk_start; + if (pipe->streaming_count) { + pipe->streaming_count++; + return 0; } + ret = media_graph_walk_init(&pipe->graph, mdev); + if (ret) + return ret; + media_graph_walk_start(&pipe->graph, entity); while ((entity = media_graph_walk_next(graph))) { DECLARE_BITMAP(active, MEDIA_ENTITY_MAX_PADS); DECLARE_BITMAP(has_no_links, MEDIA_ENTITY_MAX_PADS); - entity->stream_count++; - if (entity->pipe && entity->pipe != pipe) { pr_err("Pipe active for %s. Can't start for %s\n", entity->name, @@ -418,12 +419,12 @@ __must_check int __media_pipeline_start(struct media_entity *entity, goto error; } - entity->pipe = pipe; - /* Already streaming --- no need to check. */ - if (entity->stream_count > 1) + if (entity->pipe) continue; + entity->pipe = pipe; + if (!entity->ops || !entity->ops->link_validate) continue; @@ -479,6 +480,8 @@ __must_check int __media_pipeline_start(struct media_entity *entity, } } + pipe->streaming_count++; + return 0; error: @@ -489,24 +492,17 @@ __must_check int __media_pipeline_start(struct media_entity *entity, media_graph_walk_start(graph, entity_err); while ((entity_err = media_graph_walk_next(graph))) { - /* Sanity check for negative stream_count */ - if (!WARN_ON_ONCE(entity_err->stream_count <= 0)) { - entity_err->stream_count--; - if (entity_err->stream_count == 0) - entity_err->pipe = NULL; - } + entity_err->pipe = NULL; /* - * We haven't increased stream_count further than this - * so we quit here. + * We haven't started entities further than this so we quit + * here. */ if (entity_err == entity) break; } -error_graph_walk_start: - if (!--pipe->streaming_count) - media_graph_walk_cleanup(graph); + media_graph_walk_cleanup(graph); return ret; } @@ -537,19 +533,15 @@ void __media_pipeline_stop(struct media_entity *entity) if (WARN_ON(!pipe)) return; + if (--pipe->streaming_count) + return; + media_graph_walk_start(graph, entity); - while ((entity = media_graph_walk_next(graph))) { - /* Sanity check for negative stream_count */ - if (!WARN_ON_ONCE(entity->stream_count <= 0)) { - entity->stream_count--; - if (entity->stream_count == 0) - entity->pipe = NULL; - } - } + while ((entity = media_graph_walk_next(graph))) + entity->pipe = NULL; - if (!--pipe->streaming_count) - media_graph_walk_cleanup(graph); + media_graph_walk_cleanup(graph); } EXPORT_SYMBOL_GPL(__media_pipeline_stop); diff --git a/include/media/media-entity.h b/include/media/media-entity.h index 8546f13c42a9..e3c4fd1e3623 100644 --- a/include/media/media-entity.h +++ b/include/media/media-entity.h @@ -268,7 +268,6 @@ enum media_entity_type { * @pads: Pads array with the size defined by @num_pads. * @links: List of data links. * @ops: Entity operations. - * @stream_count: Stream count for the entity. * @use_count: Use count for the entity. * @pipe: Pipeline this entity belongs to. * @info: Union with devnode information. Kept just for backward @@ -283,10 +282,9 @@ enum media_entity_type { * * .. note:: * - * @stream_count and @use_count reference counts must never be - * negative, but are signed integers on purpose: a simple ``WARN_ON(<0)`` - * check can be used to detect reference count bugs that would make them - * negative. + * The @use_count reference count must never be negative, but is a signed + * integer on purpose: a simple ``WARN_ON(<0)`` check can be used to detect + * reference count bugs that would make it negative. */ struct media_entity { struct media_gobj graph_obj; /* must be first field in struct */ @@ -305,7 +303,6 @@ struct media_entity { const struct media_entity_operations *ops; - int stream_count; int use_count; struct media_pipeline *pipe; @@ -867,7 +864,7 @@ struct media_pad *media_entity_remote_pad(const struct media_pad *pad); */ static inline bool media_entity_is_streaming(const struct media_entity *entity) { - return entity->stream_count > 0; + return entity->pipe != NULL; } /**