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 80C9B1114; Wed, 27 Nov 2024 07:20:46 +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=1732692049; cv=none; b=nUk0iXMD58Ro4rqTdB57zcNbWlOe9vJk5Yg0N7qMoyBQ+mltnMEypK2sfn6eral7xlsTdrJnHolfBBAZKOzbIbzjViPNLdMm8VGhoOks/ULXC3+gAkFtnFT7p7UpTs1Ew+VLRdoGGxx0uF4YpyaRiadDO+R6iTSst34eeqFg80s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732692049; c=relaxed/simple; bh=r/r7QDL8mYdjc58rX7H9V4xAVcCbZj8AvPk08b/x2eI=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=bGgkg3d+6cNeG7MqgRXna8Sdkx3Y9cVEA5OovbDIh9Jg4LH91ZCWRsk7H93YSte1eQ6LICLJ1JQr8gePsg8M17DdJziWq9DnaWSNH3FqbtlBHwAlORDCIQZfx3GaHeGmjLIs003X++qPj4x7+H8+vy+lyeoH2tdIkXs1su+6beE= 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=eFeyHtPI; 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="eFeyHtPI" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id ED45F78C; Wed, 27 Nov 2024 08:20:20 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1732692021; bh=r/r7QDL8mYdjc58rX7H9V4xAVcCbZj8AvPk08b/x2eI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=eFeyHtPISvQZhkKedF3wHhaJeA5DozXxta5zpsH558wN1JXwfsMEfGbSZquQUAe7i P8bjN4Rn98hbAmE0CpgkJj3s1rtju3wW+hL8acIsKlloxhTFhv5P5nZrY25tCUC5qN ewQNEF3LeZOvWna0Ifj+Zlw1djGmAcTh/t6xs+1I= Date: Wed, 27 Nov 2024 09:20:33 +0200 From: Laurent Pinchart To: Cosmin Tanislav Cc: Mauro Carvalho Chehab , Sakari Ailus , Hans Verkuil , Tomi Valkeinen , =?utf-8?B?UGF3ZcWC?= Anikiel , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] media: v4l: subdev: Use dev_err() to print errors and clarify Message-ID: <20241127072033.GU5461@pendragon.ideasonboard.com> References: <20241122153343.237308-1-demonsingur@gmail.com> <20241123213203.GC19573@pendragon.ideasonboard.com> <09aac96d-554c-400d-9ec1-c87617d9df65@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <09aac96d-554c-400d-9ec1-c87617d9df65@gmail.com> On Mon, Nov 25, 2024 at 10:34:40PM +0200, Cosmin Tanislav wrote: > On 11/23/24 11:32 PM, Laurent Pinchart wrote: > > On Fri, Nov 22, 2024 at 05:33:39PM +0200, Cosmin Tanislav wrote: > >> The error values end up being returned to userspace, it makes sense to > >> have some useful information printed when debugging them, even if the > >> reason for the errors are bad configs or internal driver issues. > >> > >> Replace dev_dbg() with dev_err() for errors. > > > > We use dev_dbg() on purpose for all errors that can be triggered > > directly by applications. This includes in particular all pipeline > > validation errors. > > > > The error paths in this specific patch shouldn't be in that category, as > > all the validation should have been performed before starting subdevs > > (assuming all drivers are correctly implemented, which is of course not > > a given, but those issues should be fixed). I think we could therefore > > switch to dev_err() here. However, I'm wondering what kind of issues > > triggered this patch. What errors did you run into that would have > > benefited from being reported more loudly, and were they caused by > > driver bugs or userspace misconfiguring the device ? > > I've had this patch in my GMSL2 tree for some time now, I believe indeed > the reasons why I've hit these error cases were the drivers being > slightly broken, but I still think it is worthwhile to show an error > message, to aid with debugging. Adding the entity name to the messages > makes it even more clear where exactly the code is breaking. > > I can split it up into separate patches for dev_dbg() -> dev_err() and > adding the entity name to the print statements for V2. I'm OK either way. If other people prefer keeping dev_dbg() then splitting the patch in two would make sense. > >> Also, when using complex pipelines with multiple bridges between the > >> video device and multiple source sub devices, printing just the video > >> device name for each error does not provide enough context as to which > >> operation failed. > >> > >> Add sub device entity name to the messages where possible to clarify the > >> source of the errors. > > > > This can be considered as a standalone patch. > > > >> Signed-off-by: Cosmin Tanislav > >> --- > >> drivers/media/v4l2-core/v4l2-subdev.c | 22 ++++++++++++---------- > >> 1 file changed, 12 insertions(+), 10 deletions(-) > >> > >> diff --git a/drivers/media/v4l2-core/v4l2-subdev.c b/drivers/media/v4l2-core/v4l2-subdev.c > >> index 4f0eecd7fd66f..d51b4594d11c5 100644 > >> --- a/drivers/media/v4l2-core/v4l2-subdev.c > >> +++ b/drivers/media/v4l2-core/v4l2-subdev.c > >> @@ -2303,20 +2303,21 @@ int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad, > >> &found_streams, &enabled_streams); > >> > >> if (found_streams != streams_mask) { > >> - dev_dbg(dev, "streams 0x%llx not found on %s:%u\n", > >> + dev_err(dev, "streams 0x%llx not found on %s:%u\n", > >> streams_mask & ~found_streams, sd->entity.name, pad); > >> ret = -EINVAL; > >> goto done; > >> } > >> > >> if (enabled_streams) { > >> - dev_dbg(dev, "streams 0x%llx already enabled on %s:%u\n", > >> + dev_err(dev, "streams 0x%llx already enabled on %s:%u\n", > >> enabled_streams, sd->entity.name, pad); > >> ret = -EALREADY; > >> goto done; > >> } > >> > >> - dev_dbg(dev, "enable streams %u:%#llx\n", pad, streams_mask); > >> + dev_dbg(dev, "enable streams %s:%u:%#llx\n", > >> + sd->entity.name, pad, streams_mask); > >> > >> already_streaming = v4l2_subdev_is_streaming(sd); > >> > >> @@ -2333,8 +2334,8 @@ int v4l2_subdev_enable_streams(struct v4l2_subdev *sd, u32 pad, > >> } > >> > >> if (ret) { > >> - dev_dbg(dev, "enable streams %u:%#llx failed: %d\n", pad, > >> - streams_mask, ret); > >> + dev_err(dev, "enable streams %s:%u:%#llx failed: %d\n", > >> + sd->entity.name, pad, streams_mask, ret); > >> goto done; > >> } > >> > >> @@ -2403,20 +2404,21 @@ int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad, > >> &found_streams, &enabled_streams); > >> > >> if (found_streams != streams_mask) { > >> - dev_dbg(dev, "streams 0x%llx not found on %s:%u\n", > >> + dev_err(dev, "streams 0x%llx not found on %s:%u\n", > >> streams_mask & ~found_streams, sd->entity.name, pad); > >> ret = -EINVAL; > >> goto done; > >> } > >> > >> if (enabled_streams != streams_mask) { > >> - dev_dbg(dev, "streams 0x%llx already disabled on %s:%u\n", > >> + dev_err(dev, "streams 0x%llx already disabled on %s:%u\n", > >> streams_mask & ~enabled_streams, sd->entity.name, pad); > >> ret = -EALREADY; > >> goto done; > >> } > >> > >> - dev_dbg(dev, "disable streams %u:%#llx\n", pad, streams_mask); > >> + dev_dbg(dev, "disable streams %s:%u:%#llx\n", > >> + sd->entity.name, pad, streams_mask); > >> > >> if (!use_s_stream) { > >> /* Call the .disable_streams() operation. */ > >> @@ -2432,8 +2434,8 @@ int v4l2_subdev_disable_streams(struct v4l2_subdev *sd, u32 pad, > >> } > >> > >> if (ret) { > >> - dev_dbg(dev, "disable streams %u:%#llx failed: %d\n", pad, > >> - streams_mask, ret); > >> + dev_err(dev, "disable streams %s:%u:%#llx failed: %d\n", > >> + sd->entity.name, pad, streams_mask, ret); > >> goto done; > >> } > >> -- Regards, Laurent Pinchart