From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-13.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 23BA7C433DF for ; Mon, 25 May 2020 10:46:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id F04C620823 for ; Mon, 25 May 2020 10:46:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389880AbgEYKqC (ORCPT ); Mon, 25 May 2020 06:46:02 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389484AbgEYKqB (ORCPT ); Mon, 25 May 2020 06:46:01 -0400 Received: from bhuna.collabora.co.uk (bhuna.collabora.co.uk [IPv6:2a00:1098:0:82:1000:25:2eeb:e3e3]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A578FC061A0E for ; Mon, 25 May 2020 03:46:01 -0700 (PDT) Received: from [IPv6:2003:cb:871f:5b00:450d:7f43:38d6:51e8] (p200300cb871f5b00450d7f4338d651e8.dip0.t-ipconnect.de [IPv6:2003:cb:871f:5b00:450d:7f43:38d6:51e8]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: dafna) by bhuna.collabora.co.uk (Postfix) with ESMTPSA id 8024726773B; Mon, 25 May 2020 11:45:59 +0100 (BST) Subject: Re: [PATCH v4 2/5] media: v4l2-common: add helper functions to call s_stream() callbacks To: Sakari Ailus Cc: linux-media@vger.kernel.org, laurent.pinchart@ideasonboard.com, helen.koike@collabora.com, ezequiel@collabora.com, hverkuil@xs4all.nl, kernel@collabora.com, dafna3@gmail.com, linux-rockchip@lists.infradead.org, mchehab@kernel.org, tfiga@chromium.org, skhan@linuxfoundation.org, niklas.soderlund@ragnatech.se--annotate References: <20200522075522.6190-1-dafna.hirschfeld@collabora.com> <20200522075522.6190-3-dafna.hirschfeld@collabora.com> <20200525092347.GD7618@paasikivi.fi.intel.com> <3c465861-2dd3-b1d4-5492-ae6161bd63ba@collabora.com> <20200525100330.GE7618@paasikivi.fi.intel.com> From: Dafna Hirschfeld Message-ID: <7df996c6-67a3-425d-18e4-262367c1062e@collabora.com> Date: Mon, 25 May 2020 12:45:56 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200525100330.GE7618@paasikivi.fi.intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On 25.05.20 12:03, Sakari Ailus wrote: > Hi Dafna, > > On Mon, May 25, 2020 at 11:42:37AM +0200, Dafna Hirschfeld wrote: >> >> >> On 25.05.20 11:23, Sakari Ailus wrote: >>> Hi Dafna, >>> >>> My apologies for not reviewing this earlier. >> No problem :) >> >>> >>> On Fri, May 22, 2020 at 09:55:19AM +0200, Dafna Hirschfeld wrote: >>>> From: Helen Koike >>>> >>>> Add v4l2_pipeline_stream_{enable,disable} helper functions to iterate >>>> through the subdevices in a given stream (i.e following links from sink >>>> to source) and call .s_stream() callback. >>>> >>>> If .s_stream(true) fails, call .s_stream(false) in the reverse order. >>>> >>>> Signed-off-by: Helen Koike >>>> Signed-off-by: Dafna Hirschfeld >>>> --- >>>> drivers/media/v4l2-core/v4l2-common.c | 99 +++++++++++++++++++++++++++ >>>> include/media/v4l2-common.h | 39 +++++++++++ >>>> 2 files changed, 138 insertions(+) >>>> >>>> diff --git a/drivers/media/v4l2-core/v4l2-common.c b/drivers/media/v4l2-core/v4l2-common.c >>>> index 9e8eb45a5b03..734db2bf5ca9 100644 >>>> --- a/drivers/media/v4l2-core/v4l2-common.c >>>> +++ b/drivers/media/v4l2-core/v4l2-common.c >>>> @@ -442,3 +442,102 @@ int v4l2_fill_pixfmt(struct v4l2_pix_format *pixfmt, u32 pixelformat, >>>> return 0; >>>> } >>>> EXPORT_SYMBOL_GPL(v4l2_fill_pixfmt); >>>> + >>>> +#if defined(CONFIG_MEDIA_CONTROLLER) >>>> + >>>> +/* >>>> + * v4l2_pipeline_subdevs_get - Assemble a list of subdevices in a pipeline >>>> + * @subdevs: the array to be filled. >>>> + * @max_size: max number of elements that can fit in subdevs array. >>>> + * >>>> + * Walk from a video node, following links from sink to source and fill the >>>> + * array with subdevices in the path. >>>> + * The walker performs a depth-first traversal, which means that, in a topology >>>> + * sd1->sd2->sd3->vdev, sd1 will be the first element placed in the array. >>>> + * >>>> + * Return the number of subdevices filled in the array. >>>> + */ >>>> +static int v4l2_pipeline_subdevs_get(struct video_device *vdev, >>>> + struct v4l2_subdev **subdevs, >>>> + unsigned int max_size) >>>> +{ >>>> + struct media_entity *entity = &vdev->entity; >>>> + struct media_device *mdev = entity->graph_obj.mdev; >>>> + struct media_graph graph; >>>> + int idx = 0; >>>> + int ret; >>>> + >>>> + ret = media_graph_walk_init(&graph, mdev); >>>> + if (ret) >>>> + return ret; >>>> + >>>> + media_graph_walk_start(&graph, entity); >>>> + >>>> + while ((entity = media_graph_walk_next_stream(&graph))) { >>>> + if (!is_media_entity_v4l2_subdev(entity)) >>>> + continue; >>>> + if (WARN_ON(idx >= max_size)) >>>> + return -EINVAL; >>>> + subdevs[idx++] = media_entity_to_v4l2_subdev(entity); >>>> + } >>>> + >>>> + media_graph_walk_cleanup(&graph); >>>> + >>>> + return idx; >>>> +} >>>> + >>>> +static void v4l2_subdevs_stream_disable(struct v4l2_subdev **subdevs, int size) >>>> +{ >>>> + int i; >>>> + >>>> + for (i = 0; i < size; i++) { >>>> + struct v4l2_subdev *sd = subdevs[i]; >>>> + >>>> + dev_dbg(sd->dev, >>>> + "disabling stream for '%s'\n", sd->entity.name); >>>> + v4l2_subdev_call(sd, video, s_stream, false); >>>> + } >>>> +} >>>> + >>>> +__must_check int v4l2_pipeline_stream_enable(struct video_device *vdev) >>>> +{ >>>> + struct media_device *mdev = vdev->entity.graph_obj.mdev; >>>> + struct v4l2_subdev *subdevs[MEDIA_ENTITY_ENUM_MAX_DEPTH]; >>>> + struct v4l2_subdev *sd; >>>> + int i, size, ret; >>>> + >>>> + size = v4l2_pipeline_subdevs_get(vdev, subdevs, ARRAY_SIZE(subdevs)); >>>> + if (size <= 0) >>>> + return size; >>>> + >>>> + /* Call s_stream() in reverse order to enable sensors last */ >>>> + for (i = size - 1; i >= 0; i--) { >>>> + sd = subdevs[i]; >>>> + dev_dbg(mdev->dev, >>>> + "enabling stream for '%s'\n", sd->entity.name); >>>> + ret = v4l2_subdev_call(sd, video, s_stream, true); >>> >>> The s_stream callback is only called on the very next sub-device upstream >>> in the pipeline, not on any further sub-devices. This is because a driver >>> for the device knows best in which order things need to be set up. >>> >> This is only a helper function, drivers can choose not to use it. >> In many cases the same driver implements many subdevices so the driver >> knows what should be done also for subdevices deeper in the stream. > > Can it be used on devices that do not operate from memory to memory? I.e. > how do you ensure the s_stream is not called on further sub-devices than > those that are adjacent to what this driver controls? Oh, I think I see your point, for example in case of an isp driver and a sensor driver. The sensor driver can also implement several subdevices that the isp driver is not aware of and it is the responsibility of the sensor driver to call them. Is this a common case? Still there are the code parts in drivers that are implementing calling s_stream in a loop similar to those in the helper functions. Maybe they are "buggy"? For example this code part: https://git.linuxtv.org/media_tree.git/tree/drivers/media/platform/qcom/camss/camss-video.c#n430 is called by the `start_stream` of a video device and I see that the `camss_probe` function that register it also calls v4l2_async_notifier_register, which means there might have a subdevice from a different driver. Anyway, for the rkisp1 it is probably problematic since it is connected to a sensor implemented by another driver. > > One option could be to check sd->dev and skip devices that are further away > but for that you'd also need to know how these sub-devices have been > reached. The graph walk does not currently provide this information. I think it is possible to use the sd->dev (or maybe sd-owner?) since we always only go down the stream, so when we reach a subdevice from a different driver we can stop. (not sure though) Thanks, Dafna > > It's true that many drivers implement similar functionality for streaming. > It's non-trivial but often makes use of some device specific knowledge, for > instance in which order things take place (such as whether the upstream > sub-device is started before the downstream one). These implementations > also do not use graph walk for the above reasons. > >> In the cover letter of the patch there is a list of links to code parts >> that can be replaced by this helper functions. >> The cover letter: https://patchwork.kernel.org/cover/11564901/ >> >> Thanks, >> Dafna >> >>> This could include, for instance, telling a sensor to place its CSI-2 >>> transmitter to LP-11 state. >>> >>>> + if (ret && ret != -ENOIOCTLCMD) { >>>> + v4l2_subdevs_stream_disable(subdevs + i + 1, >>>> + size - i - 1); >>>> + return ret; >>>> + } >>>> + } >>>> + return 0; >>>> +} >>>> +EXPORT_SYMBOL_GPL(v4l2_pipeline_stream_enable); >>>> + >>>> +int v4l2_pipeline_stream_disable(struct video_device *vdev) >>>> +{ >>>> + struct v4l2_subdev *subdevs[MEDIA_ENTITY_ENUM_MAX_DEPTH]; >>>> + int size; >>>> + >>>> + size = v4l2_pipeline_subdevs_get(vdev, subdevs, ARRAY_SIZE(subdevs)); >>>> + if (size < 0) >>>> + return size; >>>> + >>>> + v4l2_subdevs_stream_disable(subdevs, size); >>>> + return 0; >>>> +} >>>> +EXPORT_SYMBOL_GPL(v4l2_pipeline_stream_disable); >>>> + >>>> +#endif /* CONFIG_MEDIA_CONTROLLER */ >>>> diff --git a/include/media/v4l2-common.h b/include/media/v4l2-common.h >>>> index 150ee16ebd81..a278bcf3c5bc 100644 >>>> --- a/include/media/v4l2-common.h >>>> +++ b/include/media/v4l2-common.h >>>> @@ -539,4 +539,43 @@ static inline void v4l2_buffer_set_timestamp(struct v4l2_buffer *buf, >>>> buf->timestamp.tv_usec = ts.tv_nsec / NSEC_PER_USEC; >>>> } >>>> +#if defined(CONFIG_MEDIA_CONTROLLER) >>>> + >>>> +/** >>>> + * v4l2_pipeline_stream_enable - Call .s_stream(true) callbacks in the stream >>>> + * @vdev: Starting video device. >>>> + * >>>> + * Call .s_stream(true) callback in all the subdevices participating in the >>>> + * stream, i.e. following links from sink to source. >>>> + * >>>> + * .s_stream(true) is also called from sink to source, i.e. in a topology >>>> + * sd1->sd2->sd3->vdev, .s_stream(true) of sd3 is called first. >>>> + * >>>> + * Calls to this function can be nested, in which case the same number of >>>> + * v4l2_pipeline_stream_disable() calls will be required to disable streaming >>>> + * through subdevices in the pipeline. >>>> + * The pipeline pointer must be identical for all nested calls to >>>> + * v4l2_pipeline_stream_enable(). >>>> + */ >>>> +__must_check int v4l2_pipeline_stream_enable(struct video_device *vdev); >>>> + >>>> +/** >>>> + * v4l2_pipeline_stream_disable - Call .s_stream(false) callbacks in the stream >>>> + * @vdev: Starting video device. >>>> + * >>>> + * Call .s_stream(false) callback in all the subdevices participating in the >>>> + * stream, i.e. following links from sink to source. >>>> + * >>>> + * s_stream(false) is called in a reverse order from >>>> + * v4l2_pipeline_stream_enable(), i.e. in a topology sd1->sd2->sd3->vdev, >>>> + * .s_stream(false) of sd1 is called first. >>>> + * >>>> + * If multiple calls to v4l2_pipeline_stream_enable() have been made, the same >>>> + * number of calls to this function are required to disable streaming through >>>> + * subdevices in the pipeline. >>>> + */ >>>> +int v4l2_pipeline_stream_disable(struct video_device *vdev); >>>> + >>>> +#endif /* CONFIG_MEDIA_CONTROLLER */ >>>> + >>>> #endif /* V4L2_COMMON_H_ */ >>> >