| Message ID | 20240822154531.25912-5-laurent.pinchart+renesas@ideasonboard.com (mailing list archive) |
|---|---|
| State | New |
| Headers |
Received: from am.mirrors.kernel.org ([147.75.80.249]) by linuxtv.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.96) (envelope-from <linux-media+bounces-16610-patchwork=linuxtv.org@vger.kernel.org>) id 1shA0z-0006V1-37 for patchwork@linuxtv.org; Thu, 22 Aug 2024 15:46:28 +0000 Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by am.mirrors.kernel.org (Postfix) with ESMTPS id 05B601F247DA for <patchwork@linuxtv.org>; Thu, 22 Aug 2024 15:45:59 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id A60E11386D8; Thu, 22 Aug 2024 15:45:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="VkdSXT39" X-Original-To: linux-media@vger.kernel.org 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 E131F1CCB57; Thu, 22 Aug 2024 15:45:40 +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=1724341542; cv=none; b=CrcExbCXx40qj4IWapXNeeSSb8tyv42VNh1YqYRqCPoH1w+TLZB4Yl7D4k7H4c0iGOpLEv6xyxotN7cFJzoP2jivkAngCo4XeV6U8+rAit1e8IQNTiR7HH8I0Wz3sNCiVqmGJnet5SrVsRFDWViD+rCpO9s2UQqSdVvHLZt+SLo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724341542; c=relaxed/simple; bh=L6PW/jnfXa4+nyLEP2SbfgQft2F4O8LsNw4OqltCe/g=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uVuZkjorLs5C4+yHMETNjkyhWtEoHnk7+NCpMXofw2f4czVvQCh1IqODggGCNKnUVruUTMg072EOzEb86Fq0cLhooj2NFIr+tdkaZEkwcdRaUuI3ybVWGrdo/zRjd4asmZOE+W/EjyHhGp1Fr/D5ue6ebDX2lNE+NfN1gohK32Q= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (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=VkdSXT39; arc=none smtp.client-ip=213.167.242.64 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=ideasonboard.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ideasonboard.com Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 215F5A1A; Thu, 22 Aug 2024 17:44:36 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1724341476; bh=L6PW/jnfXa4+nyLEP2SbfgQft2F4O8LsNw4OqltCe/g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VkdSXT39NT7Y6hkANIzZwqYnrmv7r+U9m93KXD4ecs92ZDQe6SXVt7p+EcFEJP8Lf 3JAyebr7y+ePsn4nIm6y2htF1dIaInEuLFbidw+7KV+IRrqL34hjhr/f7ruGx1Hpyr diwWg9ZvxMONKv0Aw1msSZLeWotjF4YfksyYlBeI= From: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> To: linux-media@vger.kernel.org Cc: Chen-Yu Tsai <wens@csie.org>, Eugen Hristev <eugen.hristev@collabora.com>, Hans Verkuil <hverkuil-cisco@xs4all.nl>, Jacopo Mondi <jacopo.mondi@ideasonboard.com>, Kieran Bingham <kieran.bingham@ideasonboard.com>, Maxime Ripard <mripard@kernel.org>, Sakari Ailus <sakari.ailus@iki.fi>, Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>, linux-renesas-soc@vger.kernel.org, linux-sunxi@lists.linux.dev Subject: [PATCH v2 4/7] media: v4l2-subdev: Refactor warnings in v4l2_subdev_link_validate() Date: Thu, 22 Aug 2024 18:45:28 +0300 Message-ID: <20240822154531.25912-5-laurent.pinchart+renesas@ideasonboard.com> X-Mailer: git-send-email 2.44.2 In-Reply-To: <20240822154531.25912-1-laurent.pinchart+renesas@ideasonboard.com> References: <20240822154531.25912-1-laurent.pinchart+renesas@ideasonboard.com> Precedence: bulk X-Mailing-List: linux-media@vger.kernel.org List-Id: <linux-media.vger.kernel.org> List-Subscribe: <mailto:linux-media+subscribe@vger.kernel.org> List-Unsubscribe: <mailto:linux-media+unsubscribe@vger.kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-LSpam-Score: -6.3 (------) X-LSpam-Report: No, score=-6.3 required=5.0 tests=ARC_SIGNED=0.001,ARC_VALID=-0.1,BAYES_00=-1.9,DKIM_SIGNED=0.1,DKIM_VALID=-0.1,DKIM_VALID_AU=-0.1,DMARC_MISSING=0.001,HEADER_FROM_DIFFERENT_DOMAINS=0.5,MAILING_LIST_MULTI=-1,RCVD_IN_VALIDITY_CERTIFIED=-3,RCVD_IN_VALIDITY_RPBL=1.31,RCVD_IN_VALIDITY_SAFE=-2,SPF_HELO_NONE=0.001,SPF_PASS=-0.001 autolearn=unavailable autolearn_force=no |
| Series |
[v2,1/7] media: microchip-isc: Drop v4l2_subdev_link_validate() for video devices
|
|
Commit Message
Laurent Pinchart
Aug. 22, 2024, 3:45 p.m. UTC
The v4l2_subdev_link_validate() function prints a one-time warning if it
gets called on a link whose source or sink is not a subdev. As links get
validated in the context of their sink, a call to the helper when the
link's sink is not a subdev indicates that the driver has set its
.link_validate() handler to v4l2_subdev_link_validate() on a non-subdev
entity, which is a clear driver bug. On the other hand, the link's
source not being a subdev indicates that the helper is used for a subdev
connected to a video output device, which is a lesser issue, if only
because this is currently common practice.
There are no drivers left in the kernel that use
v4l2_subdev_link_validate() in a context where it may get called on a
non-subdev sink. Replace the pr_warn_once() with a WARN_ON_ONCE() in
this case to make sure that new offenders won't be introduced.
Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>
---
Changes since v1:
- Switch from WARN_ON() to WARN_ON_ONCE()
---
drivers/media/v4l2-core/v4l2-subdev.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
Comments
Hi, On 22/08/2024 18:45, Laurent Pinchart wrote: > The v4l2_subdev_link_validate() function prints a one-time warning if it > gets called on a link whose source or sink is not a subdev. As links get > validated in the context of their sink, a call to the helper when the > link's sink is not a subdev indicates that the driver has set its > .link_validate() handler to v4l2_subdev_link_validate() on a non-subdev > entity, which is a clear driver bug. On the other hand, the link's > source not being a subdev indicates that the helper is used for a subdev > connected to a video output device, which is a lesser issue, if only > because this is currently common practice. Hmm, what does this mean... So we have a sink subdev, which might be linked to a source subdev (in which case everything is fine), or it might be linked to a non-subdev source. Why is it a bug to be linked to a non-subdev source? And if it is a bug, why is ok (only pr_warn_once)? Tomi > There are no drivers left in the kernel that use > v4l2_subdev_link_validate() in a context where it may get called on a > non-subdev sink. Replace the pr_warn_once() with a WARN_ON_ONCE() in > this case to make sure that new offenders won't be introduced. > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> > --- > Changes since v1: > > - Switch from WARN_ON() to WARN_ON_ONCE() > --- > drivers/media/v4l2-core/v4l2-subdev.c | 14 +++++++++----- > 1 file changed, 9 insertions(+), 5 deletions(-) > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c > index 7c5812d55315..d3196042d5c5 100644 > --- a/drivers/media/v4l2-core/v4l2-subdev.c > +++ b/drivers/media/v4l2-core/v4l2-subdev.c > @@ -1443,11 +1443,15 @@ int v4l2_subdev_link_validate(struct media_link *link) > bool states_locked; > int ret; > > - if (!is_media_entity_v4l2_subdev(link->sink->entity) || > - !is_media_entity_v4l2_subdev(link->source->entity)) { > - pr_warn_once("%s of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", > - !is_media_entity_v4l2_subdev(link->sink->entity) ? > - "sink" : "source", > + /* > + * Links are validated in the context of the sink entity. Usage of this > + * helper on a sink that is not a subdev is a clear driver bug. > + */ > + if (WARN_ON_ONCE(!is_media_entity_v4l2_subdev(link->sink->entity))) > + return -EINVAL; > + > + if (!is_media_entity_v4l2_subdev(link->source->entity)) { > + pr_warn_once("source of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", > link->source->entity->name, link->source->index, > link->sink->entity->name, link->sink->index); > return 0;
Hi Tomi, On Mon, Aug 26, 2024 at 02:10:57PM +0300, Tomi Valkeinen wrote: > On 22/08/2024 18:45, Laurent Pinchart wrote: > > The v4l2_subdev_link_validate() function prints a one-time warning if it > > gets called on a link whose source or sink is not a subdev. As links get > > validated in the context of their sink, a call to the helper when the > > link's sink is not a subdev indicates that the driver has set its > > .link_validate() handler to v4l2_subdev_link_validate() on a non-subdev > > entity, which is a clear driver bug. On the other hand, the link's > > source not being a subdev indicates that the helper is used for a subdev > > connected to a video output device, which is a lesser issue, if only > > because this is currently common practice. > > Hmm, what does this mean... So we have a sink subdev, which might be > linked to a source subdev (in which case everything is fine), or it > might be linked to a non-subdev source. > > Why is it a bug to be linked to a non-subdev source? And if it is a bug, > why is ok (only pr_warn_once)? > > > There are no drivers left in the kernel that use > > v4l2_subdev_link_validate() in a context where it may get called on a > > non-subdev sink. Replace the pr_warn_once() with a WARN_ON_ONCE() in > > this case to make sure that new offenders won't be introduced. I'll add here A subsequent change will improve the v4l2_subdev_link_validate() helper to properly support validating video device to subdev links. > > > > Signed-off-by: Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com> > > --- > > Changes since v1: > > > > - Switch from WARN_ON() to WARN_ON_ONCE() > > --- > > drivers/media/v4l2-core/v4l2-subdev.c | 14 +++++++++----- > > 1 file changed, 9 insertions(+), 5 deletions(-) > > > > diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c > > index 7c5812d55315..d3196042d5c5 100644 > > --- a/drivers/media/v4l2-core/v4l2-subdev.c > > +++ b/drivers/media/v4l2-core/v4l2-subdev.c > > @@ -1443,11 +1443,15 @@ int v4l2_subdev_link_validate(struct media_link *link) > > bool states_locked; > > int ret; > > > > - if (!is_media_entity_v4l2_subdev(link->sink->entity) || > > - !is_media_entity_v4l2_subdev(link->source->entity)) { > > - pr_warn_once("%s of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", > > - !is_media_entity_v4l2_subdev(link->sink->entity) ? > > - "sink" : "source", > > + /* > > + * Links are validated in the context of the sink entity. Usage of this > > + * helper on a sink that is not a subdev is a clear driver bug. > > + */ > > + if (WARN_ON_ONCE(!is_media_entity_v4l2_subdev(link->sink->entity))) > > + return -EINVAL; > > + > > + if (!is_media_entity_v4l2_subdev(link->source->entity)) { > > + pr_warn_once("source of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", > > link->source->entity->name, link->source->index, > > link->sink->entity->name, link->sink->index); > > return 0;
diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c index 7c5812d55315..d3196042d5c5 100644 --- a/drivers/media/v4l2-core/v4l2-subdev.c +++ b/drivers/media/v4l2-core/v4l2-subdev.c @@ -1443,11 +1443,15 @@ int v4l2_subdev_link_validate(struct media_link *link) bool states_locked; int ret; - if (!is_media_entity_v4l2_subdev(link->sink->entity) || - !is_media_entity_v4l2_subdev(link->source->entity)) { - pr_warn_once("%s of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", - !is_media_entity_v4l2_subdev(link->sink->entity) ? - "sink" : "source", + /* + * Links are validated in the context of the sink entity. Usage of this + * helper on a sink that is not a subdev is a clear driver bug. + */ + if (WARN_ON_ONCE(!is_media_entity_v4l2_subdev(link->sink->entity))) + return -EINVAL; + + if (!is_media_entity_v4l2_subdev(link->source->entity)) { + pr_warn_once("source of link '%s':%u->'%s':%u is not a V4L2 sub-device, driver bug!\n", link->source->entity->name, link->source->index, link->sink->entity->name, link->sink->index); return 0;