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 0516BC433EF for ; Sat, 25 Jun 2022 17:01:29 +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=x5/TWq5//dW8O0cUMfDWpx+wHEFT4G8l0sqRpz0vNvs=; b=iAW5ojliVIJ8ZD lp0LDUPvX4x0BnPt0etahT8Rzxwge6zzBNXydp7GaRxlWX91/LdwMfbw1a4vaOcXfIV4bHcOIidcd S+q0pMB3ykA4GiX7OX9mznjI6/pVOs3R9zmR7BkLIIP6gvIQBJSAuiCrWdbbphBp8bPbCuV+8fbFN hc7wvc/08PjHcPDoOEPi6M4ZKaS8n4hENUyMz18wuyozJjZolXVfMRB9UN6z7E7rdUgzDDIBH5e0J k96HoX6fhW6c2yx5KieFWvMKRvvwj3oZIE5C558N1SQv2DVbQ4nrVlgWTj7oroIBlAL2hZHfG5KDG HTGmxRqSDAQgXLl/3tKQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1o599l-006sV4-Un; Sat, 25 Jun 2022 17:01:13 +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 1o599h-006sTj-RS for linux-rockchip@lists.infradead.org; Sat, 25 Jun 2022 17:01:12 +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 8AA4031A; Sat, 25 Jun 2022 19:01:07 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1656176467; bh=6Du3+IGlBlFKqyOitRNOCyu4tCJZhzoq5Tnx3JgF7zw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=I4TgqHkd4sK18TpxPZ1dnHGBKDHETJiAJWIP4KC3+UaJCjswcatH1Dc+zUxyxgvyJ P8UlZTtp/uH3W7hIKxi5HS6uljBgLFfs7Kiws0LqMbOb6HpBO4POPPC35HFjmla9OS 1oWj6d/ZqFA/049Ctp6of+WnSksxfWbpNfcRKIg8= Date: Sat, 25 Jun 2022 20:00:50 +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: <6a718a13-e441-f093-d86e-5480d0a46103@xs4all.nl> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220625_100110_066655_C6CD1C5E X-CRM114-Status: GOOD ( 42.53 ) 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 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. > > 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