From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lf1-f50.google.com (mail-lf1-f50.google.com [209.85.167.50]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2889B86AED for ; Tue, 30 Jan 2024 15:41:01 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.50 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706629266; cv=none; b=HIAf26kD4GZ/j6eJA93i1iwFwI4U8h/iMovu5CKx9bONbektmoTb62nQPhergwkZ2g9fhfMkQGsCDBtXrwWHG5/+90uPa56CF5xbmEX9N/rQa6/8EckpZzubW3b4RP9OlJcuIBuhiZaHnAwT8hSLoLQ+g+9G2rlB9M6zmhsqLA4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1706629266; c=relaxed/simple; bh=5krMIBl4n0a1Z/ZhMsP0o/L7iNzPD+qczUGOcXgd0k8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=SBf5njlXp5MTtEZii46A0A1sUyLmi1LRIxa6PyhSlB2q8Jzb7AO+IDaQXjP84tX55W1DWhw175HL3nHa3Qd6S5mnZH7cftYNDNJD7959yIU9BiAyEw3y3KKprJgaihdW4TIw1AGp9lzTkN3ik9HMnHf8jAR1eGzlaMjy+KhVZj0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ragnatech.se; spf=pass smtp.mailfrom=ragnatech.se; dkim=pass (2048-bit key) header.d=ragnatech.se header.i=@ragnatech.se header.b=ey/BzR22; arc=none smtp.client-ip=209.85.167.50 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=ragnatech.se Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=ragnatech.se Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=ragnatech.se header.i=@ragnatech.se header.b="ey/BzR22" Received: by mail-lf1-f50.google.com with SMTP id 2adb3069b0e04-5102a877d50so4417975e87.0 for ; Tue, 30 Jan 2024 07:41:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ragnatech.se; s=google; t=1706629260; x=1707234060; darn=vger.kernel.org; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date:from:to :cc:subject:date:message-id:reply-to; bh=M2dQnFwI2LSx4IwikGOsCmHQ9lzvO3R64X34eGDX8QM=; b=ey/BzR220ItmuysxzCYSFawfRhOarR+abCIXOk5llEAXOpaYRNbjRxeg2xndA4ZDDG xb7we0/3jKF/w5sEdx8hijLKk6SFMXauL4eS3KgfbdfQvxy09zOSGrB7r+TLluSOwtbB 0PGS9poNIPZsH/xQtP0lYgLKZRVQtGjg6MG7DbPBXBuwgnOkvyEHdqB8NNbvbb1lcW+C 0qTKawrsE+JMDcyZa8wSx2v7pprW71ik+KczSQa2kY3uNFK7J6TN4QoiEy2ph6EFNDU/ jkh5KWH3xW3la3qfWKPuzoUjSWCeneKiNkxHhlEXiCp+FdGwt7BysturxlDTd+K1YIVU WU5A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1706629260; x=1707234060; h=in-reply-to:content-transfer-encoding:content-disposition :mime-version:references:message-id:subject:cc:to:from:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=M2dQnFwI2LSx4IwikGOsCmHQ9lzvO3R64X34eGDX8QM=; b=UpYoJ7GG/BijDcZTZX8tafrFZWLy50KsjA4AK47UUlx0dja+XYXEeOM+f3FVVM6iMG ERwYDZwVS+8P79HV/De85xV/gTfczE3GHciyNnbpPu1MHO6OAmpBIbq5VV+5FkuMEdeo KtmrPdxQ0ywJ+3JIxF4vdzh09LJS1FSG8dlUFGlAfdsttaThLlsY11Xw7yaurkoHFqzE E3mqkLzKl3OOidUupEodGoSFPoEwljJJVREMlEEXTixmQtOH00Iw1qkEs85TCTpZLX0A YQOmwhXAO4lSy+Qnv6l20CVAjDy2HAffCmNOeoLEsN3+rcE11X4acprxYToElEJSn5sX a91Q== X-Gm-Message-State: AOJu0YyBNqnsq9zEVXWp+lTi+kVY0GcBdVFxcQOmxMY5aqtk+quu8qAN 9xTon7ylPcRS+ahpw/YQ9boAPAYX6q3+RjmDIRtHhNaaXm3xSZ6uXK5NHF6qh81eNLXWAb9H4y/ QVSt9cg== X-Google-Smtp-Source: AGHT+IGTOXb5rtHZMNRQqWeGDXv0A8X4pPtz+djW3VoahcKBP6qfcZN/XX9pu2ifihI1r1oVSZnN4A== X-Received: by 2002:a19:8c4d:0:b0:50e:9e97:ce6b with SMTP id i13-20020a198c4d000000b0050e9e97ce6bmr5217294lfj.42.1706629259898; Tue, 30 Jan 2024 07:40:59 -0800 (PST) Received: from localhost (h-46-59-36-113.A463.priv.bahnhof.se. [46.59.36.113]) by smtp.gmail.com with ESMTPSA id b16-20020a056512071000b0050ecae41c51sm1481757lfs.135.2024.01.30.07.40.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 30 Jan 2024 07:40:59 -0800 (PST) Date: Tue, 30 Jan 2024 16:40:58 +0100 From: Niklas =?utf-8?Q?S=C3=B6derlund?= To: Sakari Ailus Cc: Mauro Carvalho Chehab , linux-media@vger.kernel.org, linux-renesas-soc@vger.kernel.org Subject: Re: [PATCH] media: v4l: async: Fix completion of chained subnotifiers Message-ID: <20240130154058.GC2544372@ragnatech.se> References: <20240129195954.1110643-1-niklas.soderlund+renesas@ragnatech.se> <20240130134341.GA2544372@ragnatech.se> Precedence: bulk X-Mailing-List: linux-renesas-soc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Hi Sakari, On 2024-01-30 15:27:51 +0000, Sakari Ailus wrote: > Hej Niklas, > > On Tue, Jan 30, 2024 at 02:43:41PM +0100, Niklas Söderlund wrote: > > Hi Sakari, > > > > Thanks for your feedback. > > > > On 2024-01-30 12:05:33 +0000, Sakari Ailus wrote: > > > Hi Niklas, > > > > > > Thanks for the patch. > > > > > > On Mon, Jan 29, 2024 at 08:59:54PM +0100, Niklas Söderlund wrote: > > > > Allowing multiple connections between entities are very useful but the > > > > addition of this feature did not considerate nested subnotifiers. > > > > > > > > Consider the scenario, > > > > > > > > rcar-vin.ko rcar-isp.ko rcar-csi2.ko max96712.ko > > > > > > > > video0 ----> v4l-subdev0 -> v4l-subdev1 -> v4l-subdev2 > > > > video1 -´ > > > > > > > > Where each videoX or v4l-subdevX is controlled and register by a > > > > separate instance of the driver listed above it. And each driver > > > > instance registers a notifier (videoX) or a subnotifier (v4l-subdevX) > > > > trying to bind to the device pointed to. > > > > > > > > If the devices probe in any other except where the vidoeX ones are > > > > probed last only one of them will have their complete callback called, > > > > the one who last registered its notifier. Both of them will however have > > > > their bind() callback called as expected. > > > > > > > > This is due to v4l2_async_nf_try_complete() only walking the chain from > > > > the subnotifier to one root notifier and completing it while ignoring > > > > all other notifiers the subdevice might be part of. This works if there > > > > are only one subnotifier in the mix. For example if either v4l-subdev0 > > > > or v4l-subdev1 was not part of the pipeline above. > > > > > > > > This patch addresses the issue of nested subnotifiers by instead looking > > > > at all notifiers and try to complete all the ones that contain the > > > > subdevice which subnotifier was completed. > > > > > > Why do you need this? > > > > I need this for the use-case described as an example above. In a > > separate series [1] I remove the rcar-vin workaround for the earlier > > lack of multiple connections between entities in v4l-async and without a > > solution this patch tries to address this breaks on some boards that > > already use nested subnotifiers but for which the rcar-vin workaround > > addresses. > > > > > This is also not a bug, the documentation for the complete callback says: > > > > > > * @complete: All connections have been bound successfully. The complete > > > * callback is only executed for the root notifier. > > > > Yes, and here there are two root notifiers. One in the driver > > registering video0 and the one registering video1. Both notifiers wish > > to bind to v4l-subdev0. And both notifers have their bind callback > > called when v4l-subdev0 is registered, but only one have its complete > > callback called. > > In this respect the current framework isn't perfect, it only allows one > parent... With this fix (or something like it) it works with multiple parents ;-) If it's not a bug and we drop the Fixes tag do you think this is a step in the right direction? Or shall I drop trying to solve my use-case with a solution in this area and focus on trying to work around this limitation in the driver? > > > > > > > > > Rather it would be better to get rid of this callback entirely, one reason > > > being the impossibility of error handling. We won't be there for quite some > > > time but extending its scope does go to the other direction. > > > > I agree this is the way to go. And I could do without it in my use-cases > > if I was allowed to register the video device at probe time instead of > > in the complete callback. I have brought this up over the years but > > always been told that the video device should be registered in the > > callback handler. If this is no longer true I can rework [1] and a fix > > Are you sure? > > I guess there may be differing opinions on the matter but drivers such as > ipu3-cio2 and omap3isp do it in probe. I don't think rcar-vin should be > different in this respect. Yes, I even tried to move it to probe [2] in 2017 to solve a different issue at the time. I have also discussed this in person at various conferences around that time. But 2017 was a long time ago and if you think it's now OK to register the video device at probe time I will do so work around my issue that way. But would be nice with a confirmation that this is OK before I move down that route. 2. https://lore.kernel.org/linux-renesas-soc/20170524001540.13613-16-niklas.soderlund@ragnatech.se/ > > > like this wont be needed for my use-cases. > > > > Looking beyond my use-case do you agree that as long as we do have the > > complete callback it needs to be supported for nested subnotifiers? > > > > 1. [PATCH 0/6] media: rcar-vin: Make use of multiple connections in v4l-async > > > > > > > > > > > > > Fixes: 28a1295795d8 ("media: v4l: async: Allow multiple connections between entities") > > > > Signed-off-by: Niklas Söderlund > > > > --- > > > > drivers/media/v4l2-core/v4l2-async.c | 68 ++++++++++++++++++++-------- > > > > 1 file changed, 49 insertions(+), 19 deletions(-) > > > > > > > > diff --git a/drivers/media/v4l2-core/v4l2-async.c b/drivers/media/v4l2-core/v4l2-async.c > > > > index 3ec323bd528b..8b603527923c 100644 > > > > --- a/drivers/media/v4l2-core/v4l2-async.c > > > > +++ b/drivers/media/v4l2-core/v4l2-async.c > > > > @@ -176,15 +176,16 @@ static LIST_HEAD(notifier_list); > > > > static DEFINE_MUTEX(list_lock); > > > > > > > > static struct v4l2_async_connection * > > > > -v4l2_async_find_match(struct v4l2_async_notifier *notifier, > > > > - struct v4l2_subdev *sd) > > > > +__v4l2_async_find_in_list(struct v4l2_async_notifier *notifier, > > > > + struct v4l2_subdev *sd, > > > > + struct list_head *list) > > > > { > > > > bool (*match)(struct v4l2_async_notifier *notifier, > > > > struct v4l2_subdev *sd, > > > > struct v4l2_async_match_desc *match); > > > > struct v4l2_async_connection *asc; > > > > > > > > - list_for_each_entry(asc, ¬ifier->waiting_list, asc_entry) { > > > > + list_for_each_entry(asc, list, asc_entry) { > > > > /* bus_type has been verified valid before */ > > > > switch (asc->match.type) { > > > > case V4L2_ASYNC_MATCH_TYPE_I2C: > > > > @@ -207,6 +208,20 @@ v4l2_async_find_match(struct v4l2_async_notifier *notifier, > > > > return NULL; > > > > } > > > > > > > > +static struct v4l2_async_connection * > > > > +v4l2_async_find_match(struct v4l2_async_notifier *notifier, > > > > + struct v4l2_subdev *sd) > > > > +{ > > > > + return __v4l2_async_find_in_list(notifier, sd, ¬ifier->waiting_list); > > > > +} > > > > + > > > > +static struct v4l2_async_connection * > > > > +v4l2_async_find_done(struct v4l2_async_notifier *notifier, > > > > + struct v4l2_subdev *sd) > > > > +{ > > > > + return __v4l2_async_find_in_list(notifier, sd, ¬ifier->done_list); > > > > +} > > > > + > > > > /* Compare two async match descriptors for equivalence */ > > > > static bool v4l2_async_match_equal(struct v4l2_async_match_desc *match1, > > > > struct v4l2_async_match_desc *match2) > > > > @@ -274,13 +289,14 @@ v4l2_async_nf_can_complete(struct v4l2_async_notifier *notifier) > > > > } > > > > > > > > /* > > > > - * Complete the master notifier if possible. This is done when all async > > > > + * Complete the master notifiers if possible. This is done when all async > > > > * sub-devices have been bound; v4l2_device is also available then. > > > > */ > > > > static int > > > > v4l2_async_nf_try_complete(struct v4l2_async_notifier *notifier) > > > > { > > > > - struct v4l2_async_notifier *__notifier = notifier; > > > > + struct v4l2_async_notifier *n; > > > > + int ret; > > > > > > > > /* Quick check whether there are still more sub-devices here. */ > > > > if (!list_empty(¬ifier->waiting_list)) > > > > @@ -290,24 +306,38 @@ v4l2_async_nf_try_complete(struct v4l2_async_notifier *notifier) > > > > dev_dbg(notifier_dev(notifier), > > > > "v4l2-async: trying to complete\n"); > > > > > > > > - /* Check the entire notifier tree; find the root notifier first. */ > > > > - while (notifier->parent) > > > > - notifier = notifier->parent; > > > > + /* > > > > + * Notifiers without a parent are either a subnotifier that have not > > > > + * yet been associated with it is a root notifier or a root notifier > > > > + * itself. If it is a root notifier try to complete it. > > > > + */ > > > > + if (!notifier->parent) { > > > > + /* This is root if it has v4l2_dev. */ > > > > + if (!notifier->v4l2_dev) { > > > > + dev_dbg(notifier_dev(notifier), > > > > + "v4l2-async: V4L2 device not available\n"); > > > > + return 0; > > > > + } > > > > > > > > - /* This is root if it has v4l2_dev. */ > > > > - if (!notifier->v4l2_dev) { > > > > - dev_dbg(notifier_dev(__notifier), > > > > - "v4l2-async: V4L2 device not available\n"); > > > > - return 0; > > > > - } > > > > + /* Is everything ready? */ > > > > + if (!v4l2_async_nf_can_complete(notifier)) > > > > + return 0; > > > > + > > > > + dev_dbg(notifier_dev(notifier), "v4l2-async: complete\n"); > > > > > > > > - /* Is everything ready? */ > > > > - if (!v4l2_async_nf_can_complete(notifier)) > > > > - return 0; > > > > + return v4l2_async_nf_call_complete(notifier); > > > > + } > > > > > > > > - dev_dbg(notifier_dev(__notifier), "v4l2-async: complete\n"); > > > > + /* Try to complete all notifiers containing the subdevices. */ > > > > + list_for_each_entry(n, ¬ifier_list, notifier_entry) { > > > > + if (v4l2_async_find_done(n, notifier->sd)) { > > > > + ret = v4l2_async_nf_try_complete(n); > > > > + if (ret) > > > > + return ret; > > > > + } > > > > + } > > > > > > > > - return v4l2_async_nf_call_complete(notifier); > > > > + return 0; > > > > } > > > > > > > > static int > > > > > -- > Hälsningar, > > Sakari Ailus -- Kind Regards, Niklas Söderlund