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 A5D56364D6; Fri, 13 Dec 2024 09:34:31 +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=1734082473; cv=none; b=nYRk+IPh6/GWpHLu8j5Aj5aH8YlWOtz2Rt5UyKqNUXaBhWbpfEifwUmYOIy/dDF1n4/DiJ5BUDzT+NzM0Md9VEry6eDJP0dI2bB3W6ufzYk8Iq2LXn0XXR8uCD+q4y6nJ/psKvlnPNhzB1Ww7XysYMS1ydnSsGuJXELb/V8LH1M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734082473; c=relaxed/simple; bh=pgCK4GDDXjPzcmcfY2qoLfzG9vozEGd+0DlmEDRuIhg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=LF6AA1Nn49WHPA2R+uhMKOrNAVtlExsDG3+0j7seu+wqbiLnOlNf4SC7MA0uMR6rnd1/MxDETkQfis0wVxpFHcrVaOqdgmCA06ZQ2AyAK4FJR6kkB+lLPObZj6LK2wteABpCVf5AsRQSSPxQSBacnIck8ahPG3WM22mF2quT3lE= 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=FPS6igd5; 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="FPS6igd5" Received: from pendragon.ideasonboard.com (81-175-209-231.bb.dnainternet.fi [81.175.209.231]) by perceval.ideasonboard.com (Postfix) with ESMTPSA id BBB70520; Fri, 13 Dec 2024 10:33:55 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=ideasonboard.com; s=mail; t=1734082436; bh=pgCK4GDDXjPzcmcfY2qoLfzG9vozEGd+0DlmEDRuIhg=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=FPS6igd5UT9uW7x6KYbZ9rJbiTtlZioEz6Cx9hnVRy5NGvzgN82r95m74UlrgHHEV 8k5Bnc85lqy6XDOhuf2d9xThNFvkEPTJMSfpGDX4dGsuyExDPC6sdfWeR8Rv9lSeYX hEG/UNv+4bDUF5hCVb77+nw9VkIAvJ0QLWD0pUJw= Date: Fri, 13 Dec 2024 11:34:13 +0200 From: Laurent Pinchart To: Sakari Ailus Cc: Cosmin Tanislav , Mauro Carvalho Chehab , 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: <20241213093413.GB19755@pendragon.ideasonboard.com> References: <20241122153343.237308-1-demonsingur@gmail.com> <20241123213203.GC19573@pendragon.ideasonboard.com> <09aac96d-554c-400d-9ec1-c87617d9df65@gmail.com> <20241127072033.GU5461@pendragon.ideasonboard.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: On Fri, Dec 13, 2024 at 08:33:09AM +0000, Sakari Ailus wrote: > On Wed, Nov 27, 2024 at 09:20:33AM +0200, Laurent Pinchart wrote: > > 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. > > dev_dbg() seems the correct function here: these are user-triggerable > errors that aren't related to hardware conditions. Are these user-triggerable in the absence of bugs in drivers ? > > > >> 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