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=-2.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 autolearn=no 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 EBB6BC32751 for ; Sat, 10 Aug 2019 03:51:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B0B59208C4 for ; Sat, 10 Aug 2019 03:51:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726121AbfHJDvw (ORCPT ); Fri, 9 Aug 2019 23:51:52 -0400 Received: from bhuna.collabora.co.uk ([46.235.227.227]:59588 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725927AbfHJDvv (ORCPT ); Fri, 9 Aug 2019 23:51:51 -0400 Received: from [127.0.0.1] (localhost [127.0.0.1]) (Authenticated sender: koike) with ESMTPSA id 3B19028CF0B Subject: Re: [PATCH 0/3] Collapse vimc into single monolithic driver To: =?UTF-8?Q?Andr=c3=a9_Almeida?= , Shuah Khan , mchehab@kernel.org, hverkuil@xs4all.nl, laurent.pinchart@ideasonboard.com Cc: linux-kernel@vger.kernel.org, linux-media@vger.kernel.org, kernel@collabora.com References: <3118bc46-14ac-8015-9a6c-a8dfcdcea940@collabora.com> <4e9b8eb3-23c5-62ea-07dc-b51acb238dee@linuxfoundation.org> <15badf5e-49fa-7fbe-de6b-296e9a7f5cd9@collabora.com> From: Helen Koike Openpgp: preference=signencrypt Autocrypt: addr=helen.koike@collabora.com; keydata= mQINBFmOMD4BEADb2nC8Oeyvklh+ataw2u/3mrl+hIHL4WSWtii4VxCapl9+zILuxFDrxw1p XgF3cfx7g9taWBrmLE9VEPwJA6MxaVnQuDL3GXxTxO/gqnOFgT3jT+skAt6qMvoWnhgurMGH wRaA3dO4cFrDlLsZIdDywTYcy7V2bou81ItR5Ed6c5UVX7uTTzeiD/tUi8oIf0XN4takyFuV Rf09nOhi24bn9fFN5xWHJooFaFf/k2Y+5UTkofANUp8nn4jhBUrIr6glOtmE0VT4pZMMLT63 hyRB+/s7b1zkOofUGW5LxUg+wqJXZcOAvjocqSq3VVHcgyxdm+Nv0g9Hdqo8bQHC2KBK86VK vB+R7tfv7NxVhG1sTW3CQ4gZb0ZugIWS32Mnr+V+0pxci7QpV3jrtVp5W2GA5HlXkOyC6C7H Ao7YhogtvFehnlUdG8NrkC3HhCTF8+nb08yGMVI4mMZ9v/KoIXKC6vT0Ykz434ed9Oc9pDow VUqaKi3ey96QczfE4NI029bmtCY4b5fucaB/aVqWYRH98Jh8oIQVwbt+pY7cL5PxS7dQ/Zuz 6yheqDsUGLev1O3E4R8RZ8jPcfCermL0txvoXXIA56t4ZjuHVcWEe2ERhLHFGq5Zw7KC6u12 kJoiZ6WDBYo4Dp+Gd7a81/WsA33Po0j3tk/8BWoiJCrjXzhtRwARAQABtCdIZWxlbiBLb2lr ZSA8aGVsZW4ua29pa2VAY29sbGFib3JhLmNvbT6JAlQEEwEKAD4CGwEFCwkIBwMFFQoJCAsF FgIDAQACHgECF4AWIQSofQA6zrItXEgHWTzAfqwo9yFiXQUCXEz3bwUJBKaPRQAKCRDAfqwo 9yFiXdUCD/4+WZr503hQ13KB4DijOW76ju8JDPp4p++qoPxtoAsld3yROoTI+VPWmt7ojHrr TZc7sTLxOFzaUC8HjGTb3r9ilIhIKf/M9KRLkpIJ+iLA+VoUbcSOMYWoVNfgLmbnqoezjPcy OHJwVw9dzEeYpvG6nkY6E4UktANySp27AniSXNuHOvYsOsXmUOqU1ScdsrQ9s732p/OGdTyw 1yd3gUMLZvCKFOBVHILH59HCRJgpwUPiws8G4dGMs4GTRvHT2s2mDQdQ0HEvcM9rvCRVixuC 5ZeOymZNi6lDIUIysgiZ+yzk6i5l/Ni6r7v20N3JppZvhPK6LqtaYceyAGyc3jjnOqoHT/qR kPjCwzmKiPtXjLw6HbRXtGgGtP5m3y8v6bfHH+66zd2vGCY0Z9EsqcnK4DCqRkLncFLPM2gn 9cZcCmO4ZqXUhTyn1nHM494kd5NX1Op4HO+t9ErnpufkVjoMUeBwESdQwwwHT3rjUueGmCrn VJK69/qhA4La72VTxHutl+3Z0Xy20HWsZS8Gsam39f95/LtPLzbBwnOOi5ZoXnm97tF8HrAZ 2h+kcRLMWw3BXy5q4gic+oFZMZP9oq1G9XTFld4FGgJ9ys8aGmhLM+uB1pFxb3XFtWQ2z4AJ iEp2VLl34quwfD6Gg4csiZe2KzvQHUe0w8SJ9LplrHPPprkCDQRZjjChARAAzISLQaHzaDOv ZxcoCNBk/hUGo2/gsmBW4KSj73pkStZ+pm3Yv2CRtOD4jBlycXjzhwBV7/70ZMH70/Y25dJa CnJKl/Y76dPPn2LDWrG/4EkqUzoJkhRIYFUTpkPdaVYznqLgsho19j7HpEbAum8r3jemYBE1 AIuVGg4bqY3UkvuHWLVRMuaHZNy55aYwnUvd46E64JH7O990mr6t/nu2a1aJ0BDdi8HZ0RMo Eg76Avah+YR9fZrhDFmBQSL+mcCVWEbdiOzHmGYFoToqzM52wsNEpo2aStH9KLk8zrCXGx68 ohJyQoALX4sS03RIWh1jFjnlw2FCbEdj/HDX0+U0i9COtanm54arYXiBTnAnx0F7LW7pv7sb 6tKMxsMLmprP/nWyV5AfFRi3jxs5tdwtDDk/ny8WH6KWeLR/zWDwpYgnXLBCdg8l97xUoPQO 0VkKSa4JEXUZWZx9q6kICzFGsuqApqf9gIFJZwUmirsxH80Fe04Tv+IqIAW7/djYpOqGjSyk oaEVNacwLLgZr+/j69/1ZwlbS8K+ChCtyBV4kEPzltSRZ4eU19v6sDND1JSTK9KSDtCcCcAt VGFlr4aE00AD/aOkHSylc93nPinBFO4AGhcs4WypZ3GGV6vGWCpJy9svfWsUDhSwI7GS/i/v UQ1+bswyYEY1Q3DjJqT7fXcAEQEAAYkEcgQYAQoAJgIbAhYhBKh9ADrOsi1cSAdZPMB+rCj3 IWJdBQJcTPfVBQkEpo7hAkDBdCAEGQEKAB0WIQSomGMEg78Cd/pMshveCRfNeJ05lgUCWY4w oQAKCRDeCRfNeJ05lp0gD/49i95kPKjpgjUbYeidjaWuINXMCA171KyaBAp+Jp2Qrun4sIJB Z6srMj6O/gC34AhZln2sXeQdxe88sNbg6HjlN+4AkhTd6DttjOfUwnamLDA7uw+YIapGgsgN lznjLnqOaQ9mtEwRbZMUOdyRf9osSuL14vHl4ia3bYNJ52WYre6gLMu4K+Ghd02og+ILgIio Q827h0spqIJYHrR3Ynnhxdlv5GPCobh+AKsQMdTIuCzR6JSCBk6GHkg33SiWScKMUzT8B/cn ypLfGnfV/LDZ9wS2TMzIlK/uv0Vd4C0OGDd/GCi5Gwu/Ot0aY7fzZo2CiRV+/nJBWPRRBTji bE4FG2rt7WSRLO/QmH2meIW4f0USDiHeNwznHkPei59vRdlMyQdsxrmgSRDuX9Y3UkERxbgd uscqC8Cpcy5kpF11EW91J8aGpcxASc+5Pa66/+7CrpBC2DnfcfACdMAje7yeMn9XlHrqXNlQ GaglEcnGN2qVqRcKgcjJX+ur8l56BVpBPFYQYkYkIdQAuhlPylxOvsMcqI6VoEWNt0iFF3dA //0MNb8fEqw5TlxDPOt6BDhDKowkxOGIA9LOcF4PkaR9Qkvwo2P4vA/8fhCnMqlSPom4xYdk Ev8P554zDoL/XMHl+s7A0MjIJzT253ejZKlWeO68pAbNy/z7QRn2lFDnjwkQwH6sKPchYl2f 0g//Yu3vDkqk8+mi2letP3XBl2hjv2eCZjTh34VvtgY5oeL2ROSJWNd18+7O6q3hECZ727EW gIb3LK9g4mKF6+Rch6Gwz1Y4fmC5554fd2Y2XbVzzz6AGUC6Y+ohNg7lTAVO4wu43+IyTB8u ip5rX/JDGFv7Y1sl6tQJKAVIKAJE+Z3Ncqh3doQr9wWHl0UiQYKbSR9HpH1lmC1C3EEbTpwK fUIpZd1eQNyNJl1jHsZZIBYFsAfVNH/u6lB1TU+9bSOsV5SepdIb88d0fm3oZ4KzjhRHLFQF RwNUNn3ha6x4fbxYcwbvu5ZCiiX6yRTPoage/LUNkgQNX2PtPcur6CdxK6Pqm8EAI7PmYLfN NY3y01XhKNRvaVZoH2FugfUkhsBITglTIpI+n6YU06nDAcbeINFo67TSE0iL6Pek5a6gUQQC 6w+hJCaMr8KYud0q3ccHyU3TlAPDe10En3GsVz7Y5Sa3ODGdbmkfjK8Af3ogGNBVmpV16Xl8 4rETFv7POSUB2eMtbpmBopd+wKqHCwUEy3fx1zDbM9mp+pcDoL73rRZmlgmNfW/4o4qBzxRf FYTQLE69wAFU2IFce9PjtUAlBdC+6r3X24h3uD+EC37s/vWhxuKj2glaU9ONrVJ/SPvlqXOO WR1Zqw57vHMKimLdG3c24l8PkSw1usudgAA5OyO5Ag0EWY4wyQEQAMVp0U38Le7d80Mu6AT+ 1dMes87iKn30TdMuLvSg2uYqJ1T2riRBF7zU6u74HF6zps0rPQviBXOgoSuKa1hnS6OwFb9x yQPlk76LY96SUB5jPWJ3fO78ZGSwkVbJFuG9gpD/41n8Unn1hXgDb2gUaxD0oXv/723EmTYC vSo3z6Y8A2aBQNr+PyhQAPDazvVQ+P7vnZYq1oK0w+D7aIix/Bp4mo4VbgAeAeMxXWSZs8N5 NQtXeTBgB7DqrfJP5wWwgCsROfeds6EoddcYgqhG0zVU9E54C8JcPOA0wKVs+9+gt2eyRNtx 0UhFbah7qXuJGhWy/0CLXvVoCoS+7qpWz070TBAlPZrg9D0o2gOw01trQgoKAYBKKgJhxaX/ 4gzi+5Ccm33LYH9lAVTdzdorejuV1xWdsnNyc8OAPeoXBf9RIIWfQVmbhVXBp2DAPjV6/kIJ Eml7MNJfEvqjV9zKsWF9AFlsqDWZDCyUdqR96ahTSD34pRwb6a9H99/GrjeowKaaL95DIVZT C6STvDNL6kpys4sOe2AMmQGv2MMcJB3aYLzH8f1sEQ9S0UMX7/6CifEG6JodG6Y/W/lLo1Vv DxeDA+u4Lgq6qxlksp8M78FjcmxFVlf4cpCi2ucbZxurhlBkjtZZ8MVAEde3hlqjcBl2Ah6Q D826FTxscOGlHEfNABEBAAGJAjwEGAEKACYCGwwWIQSofQA6zrItXEgHWTzAfqwo9yFiXQUC XEz31QUJBKaOuQAKCRDAfqwo9yFiXUvnEACBWe8wSnIvSX+9k4LxuLq6GQTOt+RNfliZQkCW 5lT3KL1IJyzzOm4x+/slHRBl8bF7KEZyOPinXQXyJ/vgIdgSYxDqoZ7YZn3SvuNe4aT6kGwL EYYEV8Ecj4ets15FR2jSUNnVv5YHWtZ7bP/oUzr2LT54fjRcstYxgwzoj8AREtHQ4EJWAWCO ZuEHTSm5clMFoi41CmG4DlJbzbo4YfilKYm69vwh50Y8WebcRN31jh0g8ufjOJnBldYYBLwN Obymhlfy/HKBDIbyCGBuwYoAkoJ6LR/cqzl/FuhwhuDocCGlXyYaJOwXgHaCvVXI3PLQPxWZ +vPsD+TSVHc9m/YWrOiYDnZn6aO0Uk1Zv/m9+BBkWAwsreLJ/evn3SsJV1omNBTITG+uxXcf JkgmmesIAw8mpI6EeLmReUJLasz8QkzhZIC7t5rGlQI94GQG3Jg2dC+kpaGWOaT5G4FVMcBj iR1nXfMxENVYnM5ag7mBZyD/kru5W1Uj34L6AFaDMXFPwedSCpzzqUiHb0f+nYkfOodf5xy0 46+3THy/NUS/ZZp/rI4F7Y77+MQPVg7vARfHHX1AxYUKfRVW5j88QUB70txn8Vgi1tDrOr4J eD+xr0CvIGa5lKqgQacQtGkpOpJ8zY4ObSvpNubey/qYUE3DCXD0n2Xxk4muTvqlkFpOYA== Message-ID: Date: Sat, 10 Aug 2019 00:51:36 -0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: <15badf5e-49fa-7fbe-de6b-296e9a7f5cd9@collabora.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Andre, Thanks for testing this. On 8/9/19 9:24 PM, André Almeida wrote: > On 8/9/19 9:17 PM, Shuah Khan wrote: >> Hi Andre, >> >> On 8/9/19 5:52 PM, André Almeida wrote: >>> Hello Shuah, >>> >>> Thanks for the patch, I did some comments below. >>> >>> On 8/9/19 6:45 PM, Shuah Khan wrote: >>>> vimc uses Component API to split the driver into functional components. >>>> The real hardware resembles a monolith structure than component and >>>> component structure added a level of complexity making it hard to >>>> maintain without adding any real benefit. >>>>      The sensor is one vimc component that would makes sense to be a >>>> separate >>>> module to closely align with the real hardware. It would be easier to >>>> collapse vimc into single monolithic driver first and then split the >>>> sensor off as a separate module. >>>> >>>> This patch series emoves the component API and makes minimal changes to >>>> the code base preserving the functional division of the code structure. >>>> Preserving the functional structure allows us to split the sensor off >>>> as a separate module in the future. >>>> >>>> Major design elements in this change are: >>>>      - Use existing struct vimc_ent_config and struct >>>> vimc_pipeline_config >>>>        to drive the initialization of the functional components. >>>>      - Make vimc_ent_config global by moving it to vimc.h >>>>      - Add two new hooks add and rm to initialize and register, >>>> unregister >>>>        and free subdevs. >>>>      - All component API is now gone and bind and unbind hooks are >>>> modified >>>>        to do "add" and "rm" with minimal changes to just add and rm >>>> subdevs. >>>>      - vimc-core's bind and unbind are now register and unregister. >>>>      - vimc-core invokes "add" hooks from its vimc_register_devices(). >>>>        The "add" hooks remain the same and register subdevs. They don't >>>>        create platform devices of their own and use vimc's pdev.dev as >>>>        their reference device. The "add" hooks save their >>>> vimc_ent_device(s) >>>>        in the corresponding vimc_ent_config. >>>>      - vimc-core invokes "rm" hooks from its unregister to unregister >>>> subdevs >>>>        and cleanup. >>>>      - vimc-core invokes "add" and "rm" hooks with pointer to struct >>>> vimc_device >>>>        and the corresponding struct vimc_ent_config pointer. >>>>      The following configure and stream test works on all devices. >>>>           media-ctl -d platform:vimc -V '"Sensor >>>> A":0[fmt:SBGGR8_1X8/640x480]' >>>>      media-ctl -d platform:vimc -V '"Debayer >>>> A":0[fmt:SBGGR8_1X8/640x480]' >>>>      media-ctl -d platform:vimc -V '"Sensor >>>> B":0[fmt:SBGGR8_1X8/640x480]' >>>>      media-ctl -d platform:vimc -V '"Debayer >>>> B":0[fmt:SBGGR8_1X8/640x480]' >>>>           v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v >>>> width=1920,height=1440 >>>>      v4l2-ctl -z platform:vimc -d "Raw Capture 0" -v pixelformat=BA81 >>>>      v4l2-ctl -z platform:vimc -d "Raw Capture 1" -v pixelformat=BA81 >>>>           v4l2-ctl --stream-mmap --stream-count=100 -d /dev/video1 >>>>      v4l2-ctl --stream-mmap --stream-count=100 -d /dev/video2 >>>>      v4l2-ctl --stream-mmap --stream-count=100 -d /dev/video3 >>>> >>>> The third patch in the series fixes a general protection fault found >>>> when rmmod is done while stream is active. >>> >>> I applied your patch on top of media_tree/master and I did some testing. >>> Not sure if I did something wrong, but just adding and removing the >>> module generated a kernel panic: >> >> Thanks for testing. >> >> Odd. I tested modprobe and rmmod both.I was working on Linux 5.3-rc2. >> I will apply these to media latest and work from there. I have to >> rebase these on top of the reverts from Lucas and Helen > > Ok, please let me know if I succeeded to reproduce. > >>> >>> ~# modprobe vimc >>> ~# rmmod vimc >>> [   16.452974] stack segment: 0000 [#1] SMP PTI >>> [   16.453688] CPU: 0 PID: 2038 Comm: rmmod Not tainted 5.3.0-rc2+ #36 >>> [   16.454678] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), >>> BIOS 1.12.0-20181126_142135-anatol 04/01/2014 >>> [   16.456191] RIP: 0010:kfree+0x4d/0x240 >>> >>> >>> >>> [   16.469188] Call Trace: >>> [   16.469666]  vimc_remove+0x35/0x90 [vimc] >>> [   16.470436]  platform_drv_remove+0x1f/0x40 >>> [   16.471233]  device_release_driver_internal+0xd3/0x1b0 >>> [   16.472184]  driver_detach+0x37/0x6b >>> [   16.472882]  bus_remove_driver+0x50/0xc1 >>> [   16.473569]  vimc_exit+0xc/0xca0 [vimc] >>> [   16.474231]  __x64_sys_delete_module+0x18d/0x240 >>> [   16.475036]  do_syscall_64+0x43/0x110 >>> [   16.475656]  entry_SYSCALL_64_after_hwframe+0x44/0xa9 >>> [   16.476504] RIP: 0033:0x7fceb8dafa4b >>> >>> >>> >>> [   16.484853] Modules linked in: vimc(-) videobuf2_vmalloc >>> videobuf2_memops v4l2_tpg videobuf2_v4l2 videobuf2_common >>> [   16.486187] ---[ end trace 91e5e0894e254d49 ]--- >>> [   16.486758] RIP: 0010:kfree+0x4d/0x240 >>> >>> >>> >>> fish: “rmmod vimc” terminated by signal SIGSEGV (Address boundary error) >>> >>> I just added the module after booting, no other action was made. Here is >>> how my `git log --oneline` looks like: >>> >>> 897d708e922b media: vimc: Fix gpf in rmmod path when stream is active >>> 2e4a5ad8ad6d media: vimc: Collapse component structure into a single >>> monolithic driver >>> 7c8da1687e92 media: vimc: move private defines to a common header >>> 97299a303532 media: Remove dev_err() usage after platform_get_irq() >>> 25a3d6bac6b9 media: adv7511/cobalt: rename driver name to adv7511-v4l2 I couldn't reproduce the error, my tree looks the same: [I] koike@floko ~/m/o/linux> git log --oneline e3345155c8ed (HEAD) media: vimc: Fix gpf in rmmod path when stream is active 43e9e2fe761f media: vimc: Collapse component structure into a single monolithic driver 8a6d0b9adde0 media: vimc: move private defines to a common header 97299a303532 (media/master) media: Remove dev_err() usage after platform_get_irq() 25a3d6bac6b9 media: adv7511/cobalt: rename driver name to adv7511-v4l2 André, is this deterministic? Or it just happens sometimes? >>> ... >>> >>>> >>>> vimc_print_dot (--print-dot) topology after this change: >>>> digraph board { >>>>     rankdir=TB >>>>     n00000001 [label="{{} | Sensor A\n/dev/v4l-subdev0 | { >>>> 0}}", shape=Mrecord, style=filled, fillcolor=green] >>>>     n00000001:port0 -> n00000005:port0 [style=bold] >>>>     n00000001:port0 -> n0000000b [style=bold] >>>>     n00000003 [label="{{} | Sensor B\n/dev/v4l-subdev1 | { >>>> 0}}", shape=Mrecord, style=filled, fillcolor=green] >>>>     n00000003:port0 -> n00000008:port0 [style=bold] >>>>     n00000003:port0 -> n0000000f [style=bold] >>>>     n00000005 [label="{{ 0} | Debayer A\n/dev/v4l-subdev2 | >>>> { 1}}", shape=Mrecord, style=filled, fillcolor=green] >>>>     n00000005:port1 -> n00000015:port0 >>>>     n00000008 [label="{{ 0} | Debayer B\n/dev/v4l-subdev3 | >>>> { 1}}", shape=Mrecord, style=filled, fillcolor=green] >>>>     n00000008:port1 -> n00000015:port0 [style=dashed] >>>>     n0000000b [label="Raw Capture 0\n/dev/video1", shape=box, >>>> style=filled, fillcolor=yellow] >>>>     n0000000f [label="Raw Capture 1\n/dev/video2", shape=box, >>>> style=filled, fillcolor=yellow] >>>>     n00000013 [label="{{} | RGB/YUV Input\n/dev/v4l-subdev4 | >>>> { 0}}", shape=Mrecord, style=filled, fillcolor=green] >>>>     n00000013:port0 -> n00000015:port0 [style=dashed] >>>>     n00000015 [label="{{ 0} | Scaler\n/dev/v4l-subdev5 | >>>> { 1}}", shape=Mrecord, style=filled, fillcolor=green] >>>>     n00000015:port1 -> n00000018 [style=bold] >>>>     n00000018 [label="RGB/YUV Capture\n/dev/video3", shape=box, >>>> style=filled, fillcolor=yellow] >>>> } >>> >>> Since the topology changed, it would be nice to change in the >>> documentation as well. The current dot file can be found at >>> `Documentation/media/v4l-drivers/vimc.dot` and it's rendered at this >>> page: https://www.kernel.org/doc/html/latest/media/v4l-drivers/vimc.html >>> >> >> Topology shouldn't have changed. No changes to links or pads etc. >> I will take a look to be sure. I agree that if topology changes >> document should be updated. > > If you "diff" the current dot with the dot you generated, you will see > some differences. The main difference is that "RGB/YUV Input" was a > device "/dev/video2/", and now it a subdevice "/dev/v4l-subdev4". hmm, I just generated the topology for media/master, and it is /dev/v4l-subdev4. As we don't have an implementation of the output device yet, we used the sensor as a place holder and that is why it appears as "/dev/v4l-subdev4", what is in the docs is the ideal version after we get the output merged. We should update the docs in any case. Regards, Helen > >> >> thanks, >> -- Shuah >