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 6B21426AED for ; Mon, 26 Aug 2024 11:11:02 +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=1724670663; cv=none; b=gesm1aS1Ib3bo0IgbQuaQNXVIzs+NL3VhVguAOaxIx6H4WbJePv3sEWQ43/NMAulWh5mvPkEyp/Gae4ZED1Iuurk1lEmpQ/XqEyFYPPUBwWne9KQQLxSIQ36eDc7W9OgcFYjGp8tXAHSXoOmW8GEhGr2RO7TOm/E8wBSorkXzY4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1724670663; c=relaxed/simple; bh=RRkCScZ1WzBWErKzfPhLvRc5v4pQhCbNmabMej1eOX8=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=QZkVk5fa7i1rOsG70iFnWQ2HxIXlUGRem5SbxXlnBO7AtejhQGC30otPYejhOVRoDV0OxZUlX+bnWb/YxUFe0ba/CdLVxE0X0LUSLtUleFWpguvODAlQ8EPLje9dzd0dQQoltfFG1JLkv6Ex+P8vYycVRU7pYdyQNbCUNeRBT38= 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=aDe5occb; 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 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=ideasonboard.com header.i=@ideasonboard.com header.b="aDe5occb" Received: from [192.168.88.20] (91-156-87-48.elisa-laajakaista.fi [91.156.87.48]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id 23D72480; Mon, 26 Aug 2024 13:09:54 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1724670594; bh=RRkCScZ1WzBWErKzfPhLvRc5v4pQhCbNmabMej1eOX8=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=aDe5occbLGyxxUyyHonhQTCzuZSdZQrOiUX+HsaTRYDWqkxct248yEdRm0QiVxTNu BvxrsZOgOzr4JT+c2MgZn28SAZA1cWoXAClZ9+kKUprb1tecnA/zltIwjhzIo5ruUW +B3ckOvMDOcpUkZJhFVyY18G4SAgRo28fY1rfdX8= Message-ID: Date: Mon, 26 Aug 2024 14:10:57 +0300 Precedence: bulk X-Mailing-List: linux-sunxi@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 4/7] media: v4l2-subdev: Refactor warnings in v4l2_subdev_link_validate() To: Laurent Pinchart , linux-media@vger.kernel.org Cc: Chen-Yu Tsai , Eugen Hristev , Hans Verkuil , Jacopo Mondi , Kieran Bingham , Maxime Ripard , Sakari Ailus , linux-renesas-soc@vger.kernel.org, linux-sunxi@lists.linux.dev References: <20240822154531.25912-1-laurent.pinchart+renesas@ideasonboard.com> <20240822154531.25912-5-laurent.pinchart+renesas@ideasonboard.com> Content-Language: en-US From: Tomi Valkeinen Autocrypt: addr=tomi.valkeinen@ideasonboard.com; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit 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 > --- > 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;