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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 933A2C433EF for ; Sat, 25 Jun 2022 17:29:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ZwR/PMdra30Czi2QcP4p5tbrvIczmd/CB4lYoiJW8rA=; b=KiDd/gkAD6Z97D 3mk4qTcUoB/0JUxO8PXm60I5uIWXihoYPidKdyIVDM6WQWBxUlZpExDuRa21CDwE4GsnSdFzikxaq KKUXWBIB30XUds1UGRbtPtOY4hcDmaEP2vtDMtNbFOgZ8zuYmqJkvvmpiJ2xvcafaIAgAF964m6XB xJQuyfaOLdJqBbDz2Xp36U2MvPjYHQUpDszSaniSz7uTjnPuV0MKY92CwdCpwvv6sWzxOV1LhCNx1 AbQZbmG1JRCng1u0feIhqWHr4u2wvL2Su2RbL/zhRXRbMVxkCL4n6vly8PlMV2uyS7yzhKRNWcoq1 HCE09Osu/d9zx3AfasbQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o59ar-006ypT-Lh; Sat, 25 Jun 2022 17:29:13 +0000 Received: from perceval.ideasonboard.com ([213.167.242.64]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1o59ao-006yng-UF for linux-rockchip@lists.infradead.org; Sat, 25 Jun 2022 17:29:12 +0000 Received: from pendragon.ideasonboard.com (62-78-145-57.bb.dnainternet.fi [62.78.145.57]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 65D4631A; Sat, 25 Jun 2022 19:29:07 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1656178147; bh=NCh0oc7HvQbfIgqT7RsPtu1dGyYySnA/n4xK8KgrMmY=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=wl0hG/vZUYqnWUi29/AC0NOVlbW6i3f2pE2pz6hUZIfztAEBQYlGq/6Pin3QJ7A/H MMZRhZDSZf3qvOgs4mh7Uau1IVmMiC5GD09rezh7xW/bdeGCdLNhLbwSHXCbxSPKTg A/C+j4l1/ugvANVLPRR0Q9TV5wX1srmVOIEUh/uo= Date: Sat, 25 Jun 2022 20:28:50 +0300 From: Laurent Pinchart To: Hans Verkuil Cc: Paul Elder , linux-media@vger.kernel.org, dafna@fastmail.com, heiko@sntech.de, jeanmichel.hautbois@ideasonboard.com, jacopo@jmondi.org, djrscally@gmail.com, helen.koike@collabora.com, linux-rockchip@lists.infradead.org Subject: Re: [PATCH 37/55] media: mc-entity: Add a new helper function to get a remote pad Message-ID: References: <20220614191127.3420492-1-paul.elder@ideasonboard.com> <20220614191127.3420492-38-paul.elder@ideasonboard.com> <6a718a13-e441-f093-d86e-5480d0a46103@xs4all.nl> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220625_102911_173953_DD2A0963 X-CRM114-Status: GOOD ( 47.90 ) X-BeenThere: linux-rockchip@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Upstream kernel work for Rockchip platforms List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "Linux-rockchip" Errors-To: linux-rockchip-bounces+linux-rockchip=archiver.kernel.org@lists.infradead.org Hi Hans, On Sat, Jun 25, 2022 at 08:00:51PM +0300, Laurent Pinchart wrote: > On Fri, Jun 17, 2022 at 01:48:05PM +0200, Hans Verkuil wrote: > > On 6/14/22 21:11, Paul Elder wrote: > > > From: Laurent Pinchart > > > > > > The media_entity_remote_pad() helper function returns the first remote > > > pad it find connected to a given pad. Beside being possibly ill-named > > > (as it operates on a pad, not an entity) and non-deterministic (as it > > > stops at the first enabled link), the fact that it returns the first > > > match makes it unsuitable for drivers that need to guarantee that a > > > single link is enabled, for instance when an entity can process data > > > from one of multiple sources at a time. > > > > Question: of all the callers of this function, are there any that really > > need media_entity_remote_pad() instead of media_pad_remote_pad_unique()? > > > > Would it be possible to replace all callers of the old function with the > > new function? If that's the case, then the _unique suffix can be dropped, > > since that would effectively be the default. And if a function is needed > > to handle the case where there are multiple enabled links, then a new > > function should be created. > > I don't think so. media_entity_remote_pad() operates on a pad, switching > to media_pad_remote_pad_unique() wouldn't work on subdevs that have > multiple sink or source pads with one active link each. > > > Also, media_entity_remote_pad() should really be renamed to > > media_pad_remote_pad_first() or something like that, right? I'm not saying > > you should, but that's really what it does, as I understand it. > > Yes, I think that would make sense, and it would freethe > media_entity_remote_pad() name, so the new function wouldn't need the > _unique suffix. I'll give it a try. The rename was easy enough, but I've decided to keep the media_entity_remote_pad_unique() name and renamed media_entity_remote_source_pad() to media_entity_remote_source_pad_unique() to make the API clearer. If those names end up being too long, we can rename them later. > > > For those use cases, add a new helper function, > > > media_entity_remote_pad_unique(), that operates on an entity and returns > > > a remote pad, with a guarantee that only one link is enabled. To ease > > > its use in drivers, also add an inline wrapper that locates source pads > > > specifically. A wrapper that locates sink pads can easily be added when > > > needed. > > > > > > Signed-off-by: Laurent Pinchart > > > --- > > > Documentation/driver-api/media/mc-core.rst | 4 +- > > > drivers/media/mc/mc-entity.c | 38 ++++++++++++++++++ > > > include/media/media-entity.h | 45 ++++++++++++++++++++++ > > > 3 files changed, 85 insertions(+), 2 deletions(-) > > > > > > diff --git a/Documentation/driver-api/media/mc-core.rst b/Documentation/driver-api/media/mc-core.rst > > > index 02481a2513b9..a2d1e32e3abb 100644 > > > --- a/Documentation/driver-api/media/mc-core.rst > > > +++ b/Documentation/driver-api/media/mc-core.rst > > > @@ -186,8 +186,8 @@ is required and the graph structure can be freed normally. > > > > > > Helper functions can be used to find a link between two given pads, or a pad > > > connected to another pad through an enabled link > > > -:c:func:`media_entity_find_link()` and > > > -:c:func:`media_entity_remote_pad()`. > > > +(:c:func:`media_entity_find_link()`, :c:func:`media_entity_remote_pad()` and > > > +:c:func:`media_entity_remote_source_pad()`). > > > > > > Use count and power handling > > > ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ > > > diff --git a/drivers/media/mc/mc-entity.c b/drivers/media/mc/mc-entity.c > > > index 11f5207f73aa..1febf5a86be6 100644 > > > --- a/drivers/media/mc/mc-entity.c > > > +++ b/drivers/media/mc/mc-entity.c > > > @@ -9,6 +9,7 @@ > > > */ > > > > > > #include > > > +#include > > > #include > > > #include > > > #include > > > @@ -920,6 +921,43 @@ struct media_pad *media_entity_remote_pad(const struct media_pad *pad) > > > } > > > EXPORT_SYMBOL_GPL(media_entity_remote_pad); > > > > > > +struct media_pad * > > > +media_entity_remote_pad_unique(const struct media_entity *entity, > > > + unsigned int type) > > > +{ > > > + struct media_pad *pad = NULL; > > > + struct media_link *link; > > > + > > > + list_for_each_entry(link, &entity->links, list) { > > > + struct media_pad *local_pad; > > > + struct media_pad *remote_pad; > > > + > > > + if (!(link->flags & MEDIA_LNK_FL_ENABLED)) > > > + continue; > > > + > > > + if (type == MEDIA_PAD_FL_SOURCE) { > > > + local_pad = link->sink; > > > + remote_pad = link->source; > > > + } else { > > > + local_pad = link->source; > > > + remote_pad = link->sink; > > > + } > > > + > > > + if (local_pad->entity == entity) { > > > + if (pad) > > > + return ERR_PTR(-ENOTUNIQ); > > > + > > > + pad = remote_pad; > > > + } > > > + } > > > + > > > + if (!pad) > > > + return ERR_PTR(-ENOLINK); > > > + > > > + return pad; > > > +} > > > +EXPORT_SYMBOL_GPL(media_entity_remote_pad_unique); > > > + > > > static void media_interface_init(struct media_device *mdev, > > > struct media_interface *intf, > > > u32 gobj_type, > > > diff --git a/include/media/media-entity.h b/include/media/media-entity.h > > > index a9a1c0ec5d1c..33d5f52719a0 100644 > > > --- a/include/media/media-entity.h > > > +++ b/include/media/media-entity.h > > > @@ -859,6 +859,51 @@ struct media_link *media_entity_find_link(struct media_pad *source, > > > */ > > > struct media_pad *media_entity_remote_pad(const struct media_pad *pad); > > > > > > +/** > > > + * media_entity_remote_pad_unique - Find a remote pad connected to an entity > > > + * @entity: The entity > > > + * @type: The type of pad to find (MEDIA_PAD_FL_SINK or MEDIA_PAD_FL_SOURCE) > > > + * > > > + * Search for and return a remote pad of @type connected to @entity through an > > > + * enabled link. If multiple (or no) remote pads match these criteria, an error > > > + * is returned. > > > + * > > > + * The uniqueness constraint makes this helper function suitable for entities > > > + * that support a single active source or sink at a time. > > > + * > > > + * Return: A pointer to the remote pad, or one of the following error pointers > > > + * if an error occurs: > > > + * > > > + * * -ENOTUNIQ - Multiple links are enabled > > > + * * -ENOLINK - No connected pad found > > > + */ > > > +struct media_pad * > > > +media_entity_remote_pad_unique(const struct media_entity *entity, > > > + unsigned int type); > > > + > > > +/** > > > + * media_entity_remote_source_pad - Find a remote source pad connected to an entity > > > + * @entity: The entity > > > + * > > > + * Search for and return a remote source pad connected to @entity through an > > > + * enabled link. If multiple (or no) remote pads match these criteria, an error > > > + * is returned. > > > + * > > > + * The uniqueness constraint makes this helper function suitable for entities > > > + * that support a single active source at a time. > > > + * > > > + * Return: A pointer to the remote pad, or one of the following error pointers > > > + * if an error occurs: > > > + * > > > + * * -ENOTUNIQ - Multiple links are enabled > > > + * * -ENOLINK - No connected pad found > > > + */ > > > +static inline struct media_pad * > > > +media_entity_remote_source_pad(const struct media_entity *entity) > > > +{ > > > + return media_entity_remote_pad_unique(entity, MEDIA_PAD_FL_SOURCE); > > > +} > > > + > > > /** > > > * media_entity_is_streaming - Test if an entity is part of a streaming pipeline > > > * @entity: The entity -- Regards, Laurent Pinchart _______________________________________________ Linux-rockchip mailing list Linux-rockchip@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-rockchip