From: Sowjanya Komatineni <skomatineni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> To: Dmitry Osipenko <digetx-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>, thierry.reding-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, jonathanh-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, frankc-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org, hverkuil-qWit8jRvyhVmR6Xm/wNWPw@public.gmane.org, sakari.ailus-X3B1VOXEql0@public.gmane.org, helen.koike-ZGY8ohtN/8qB+jHODAdFcQ@public.gmane.org Cc: sboyd-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, linux-media-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-clk-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Subject: Re: [RFC PATCH v11 6/9] media: tegra: Add Tegra210 Video input driver Date: Sat, 2 May 2020 17:03:11 -0700 [thread overview] Message-ID: <b4b479ea-dd34-c78c-5813-46651d1cb4c7@nvidia.com> (raw) In-Reply-To: <b5f6a4e0-6e97-05ae-f034-b84fc5a1129a-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> On 5/2/20 3:46 PM, Sowjanya Komatineni wrote: > > On 5/2/20 1:48 PM, Dmitry Osipenko wrote: >> 02.05.2020 19:55, Sowjanya Komatineni пишет: >>> Also stop stream ioctl request happens during suspend where both >>> threads >>> will be stopped properly. done thread stop happens only after finishing >>> all outstanding buffers. >> Do you mean that V4L core takes care of stopping the streami on suspend >> and re-starting it on resume from suspend? >> >>> Stop stream request happens from streaming applications so even without >>> driver suspend/resume implementation currently, streaming will be >>> stopped prior to system suspend where both threads will be stopped >>> properly (after finishing out standing buffers) and will be resumed by >>> application on system resume >> All userspace is frozen on suspend. System suspension is transparent for >> userspace applications. I'm not sure what you're meaning here. >> >>> Also tested suspending while streaming with this unconditional >>> freeze, I >>> don't see any issue as application stops stream where v4l_streamoff >>> gets >>> executed during suspend and on resume streaming starts where >>> v4l_streamon happens. >>> >>> So, I don't see any issue with existing implementation of unconditional >>> freeze. >> I don't understand why freezing is needed at all if V4L core takes care >> of stopping the stream on suspend, what is the point? If there is no >> real point, then let's make threads non-freezable and done with that. > > video device fops unlocked_ioctl is set to video_ioctl2() in vi driver. > > video device fops unlocked_ioctl gets executed with stream off cmd > during suspend and stream on cmd during resume which eventually calls > v4l_streamoff and v4l_streamon during system suspend/resume. > > My understanding to have freezable threads is during system suspend > user space applications are frozen prior to kernel freeze and during > suspend when opened video character device node gets closed these > ioctl gets invoked and stream off during suspend and stream on during > resume happens. So probably we still need to use freezable threads to > sync with user space application when frozen before really entering > suspend. > > Will wait for Thierry/Hans comment to correct if my above > understanding is wrong and help clarify if we need freezable threads > at all in this case... > > Note: I see other drivers using freezable threads for capture drivers. I see only couple of media drivers using freezable threads. Also, referring to below article probably we don't need freezable threads. https://lwn.net/Articles/662703/ Probably we can then remove thread as freezable... > > > Assuming we use freezable threads, I was saying we don't need > conditional try_to_freeze() like you pointed because even if finish > thread freeze happens prior to frame capture initiated by start > thread, vi hardware will still continue to update this single ongoing > buffer and will finish max within 200ms and actually there is no > direct processing of this done by finish thread itself except that it > returns buffers back when done and in this case it returns back when > unfreeze/wake up happens. > > So, I don't see any issue of unconditional try_to_freeze() even with > freezable threads. > > Thanks > > Sowjanya > >
WARNING: multiple messages have this Message-ID (diff)
From: Sowjanya Komatineni <skomatineni@nvidia.com> To: Dmitry Osipenko <digetx@gmail.com>, <thierry.reding@gmail.com>, <jonathanh@nvidia.com>, <frankc@nvidia.com>, <hverkuil@xs4all.nl>, <sakari.ailus@iki.fi>, <helen.koike@collabora.com> Cc: <sboyd@kernel.org>, <linux-media@vger.kernel.org>, <devicetree@vger.kernel.org>, <linux-clk@vger.kernel.org>, <linux-tegra@vger.kernel.org>, <linux-kernel@vger.kernel.org> Subject: Re: [RFC PATCH v11 6/9] media: tegra: Add Tegra210 Video input driver Date: Sat, 2 May 2020 17:03:11 -0700 [thread overview] Message-ID: <b4b479ea-dd34-c78c-5813-46651d1cb4c7@nvidia.com> (raw) In-Reply-To: <b5f6a4e0-6e97-05ae-f034-b84fc5a1129a@nvidia.com> On 5/2/20 3:46 PM, Sowjanya Komatineni wrote: > > On 5/2/20 1:48 PM, Dmitry Osipenko wrote: >> 02.05.2020 19:55, Sowjanya Komatineni пишет: >>> Also stop stream ioctl request happens during suspend where both >>> threads >>> will be stopped properly. done thread stop happens only after finishing >>> all outstanding buffers. >> Do you mean that V4L core takes care of stopping the streami on suspend >> and re-starting it on resume from suspend? >> >>> Stop stream request happens from streaming applications so even without >>> driver suspend/resume implementation currently, streaming will be >>> stopped prior to system suspend where both threads will be stopped >>> properly (after finishing out standing buffers) and will be resumed by >>> application on system resume >> All userspace is frozen on suspend. System suspension is transparent for >> userspace applications. I'm not sure what you're meaning here. >> >>> Also tested suspending while streaming with this unconditional >>> freeze, I >>> don't see any issue as application stops stream where v4l_streamoff >>> gets >>> executed during suspend and on resume streaming starts where >>> v4l_streamon happens. >>> >>> So, I don't see any issue with existing implementation of unconditional >>> freeze. >> I don't understand why freezing is needed at all if V4L core takes care >> of stopping the stream on suspend, what is the point? If there is no >> real point, then let's make threads non-freezable and done with that. > > video device fops unlocked_ioctl is set to video_ioctl2() in vi driver. > > video device fops unlocked_ioctl gets executed with stream off cmd > during suspend and stream on cmd during resume which eventually calls > v4l_streamoff and v4l_streamon during system suspend/resume. > > My understanding to have freezable threads is during system suspend > user space applications are frozen prior to kernel freeze and during > suspend when opened video character device node gets closed these > ioctl gets invoked and stream off during suspend and stream on during > resume happens. So probably we still need to use freezable threads to > sync with user space application when frozen before really entering > suspend. > > Will wait for Thierry/Hans comment to correct if my above > understanding is wrong and help clarify if we need freezable threads > at all in this case... > > Note: I see other drivers using freezable threads for capture drivers. I see only couple of media drivers using freezable threads. Also, referring to below article probably we don't need freezable threads. https://lwn.net/Articles/662703/ Probably we can then remove thread as freezable... > > > Assuming we use freezable threads, I was saying we don't need > conditional try_to_freeze() like you pointed because even if finish > thread freeze happens prior to frame capture initiated by start > thread, vi hardware will still continue to update this single ongoing > buffer and will finish max within 200ms and actually there is no > direct processing of this done by finish thread itself except that it > returns buffers back when done and in this case it returns back when > unfreeze/wake up happens. > > So, I don't see any issue of unconditional try_to_freeze() even with > freezable threads. > > Thanks > > Sowjanya > >
next prev parent reply other threads:[~2020-05-03 0:03 UTC|newest] Thread overview: 117+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-04-29 21:59 [RFC PATCH v11 0/9] Add Tegra driver for video capture Sowjanya Komatineni 2020-04-29 21:59 ` Sowjanya Komatineni 2020-04-29 21:59 ` [RFC PATCH v11 1/9] arm64: tegra: Fix sor powergate clocks and reset Sowjanya Komatineni 2020-04-29 21:59 ` Sowjanya Komatineni 2020-04-29 21:59 ` [RFC PATCH v11 2/9] arm64: tegra: Add reset-cells to mc Sowjanya Komatineni 2020-04-29 21:59 ` Sowjanya Komatineni 2020-04-29 22:00 ` [RFC PATCH v11 3/9] dt-bindings: clock: tegra: Add clk id for CSI TPG clock Sowjanya Komatineni 2020-04-29 22:00 ` Sowjanya Komatineni 2020-04-29 22:00 ` [RFC PATCH v11 4/9] clk: tegra: Add Tegra210 CSI TPG clock gate Sowjanya Komatineni 2020-04-29 22:00 ` Sowjanya Komatineni 2020-04-29 22:00 ` [RFC PATCH v11 5/9] dt-binding: tegra: Add VI and CSI bindings Sowjanya Komatineni 2020-04-29 22:00 ` Sowjanya Komatineni 2020-04-29 22:00 ` [RFC PATCH v11 6/9] media: tegra: Add Tegra210 Video input driver Sowjanya Komatineni 2020-04-29 22:00 ` Sowjanya Komatineni 2020-04-30 13:34 ` Dmitry Osipenko 2020-04-30 19:27 ` Sowjanya Komatineni 2020-04-30 19:27 ` Sowjanya Komatineni 2020-04-30 13:43 ` Dmitry Osipenko [not found] ` <1588197606-32124-7-git-send-email-skomatineni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-04-30 13:38 ` Dmitry Osipenko 2020-04-30 13:38 ` Dmitry Osipenko [not found] ` <34a49a30-71f2-5b24-20a4-7d98ae37cefa-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2020-04-30 19:32 ` Sowjanya Komatineni 2020-04-30 19:32 ` Sowjanya Komatineni 2020-04-30 19:47 ` Dmitry Osipenko 2020-04-30 19:51 ` Sowjanya Komatineni 2020-04-30 19:51 ` Sowjanya Komatineni 2020-04-30 13:46 ` Dmitry Osipenko 2020-04-30 13:46 ` Dmitry Osipenko 2020-04-30 13:56 ` Dmitry Osipenko 2020-04-30 13:56 ` Dmitry Osipenko [not found] ` <bacc4308-4b95-f566-b80e-096ff96407b5-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2020-04-30 14:02 ` Dmitry Osipenko 2020-04-30 14:02 ` Dmitry Osipenko [not found] ` <4da289e6-036f-853b-beb4-379d6462adb0-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2020-04-30 14:13 ` Dmitry Osipenko 2020-04-30 14:13 ` Dmitry Osipenko [not found] ` <c6d54885-6f23-f60c-a17b-3481fc4d6adf-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2020-04-30 16:04 ` Sowjanya Komatineni 2020-04-30 16:04 ` Sowjanya Komatineni 2020-04-30 16:29 ` Sowjanya Komatineni 2020-04-30 16:29 ` Sowjanya Komatineni 2020-04-30 17:06 ` Sowjanya Komatineni 2020-04-30 17:06 ` Sowjanya Komatineni 2020-04-30 18:18 ` Sowjanya Komatineni 2020-04-30 18:18 ` Sowjanya Komatineni [not found] ` <47873bbd-cf90-4595-5a99-7e9113327ecc-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-04-30 19:09 ` Sowjanya Komatineni 2020-04-30 19:09 ` Sowjanya Komatineni [not found] ` <f6088e0f-4ac7-a6be-3ede-0233dc88ef2c-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-04-30 19:33 ` Dmitry Osipenko 2020-04-30 19:33 ` Dmitry Osipenko 2020-04-30 19:46 ` Sowjanya Komatineni 2020-04-30 19:46 ` Sowjanya Komatineni [not found] ` <b3238987-5e8a-32f2-7ce7-924e86bc6e9e-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-04-30 19:53 ` Sowjanya Komatineni 2020-04-30 19:53 ` Sowjanya Komatineni [not found] ` <298187f6-2425-4813-1ae1-f256c179623e-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-04-30 20:02 ` Sowjanya Komatineni 2020-04-30 20:02 ` Sowjanya Komatineni [not found] ` <9c942bc9-703e-3bbb-eeab-f37e69dc1ded-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-04-30 21:17 ` Dmitry Osipenko 2020-04-30 21:17 ` Dmitry Osipenko [not found] ` <b72b9d5c-7d02-1b58-20f7-30f94e230d58-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2020-04-30 21:26 ` Sowjanya Komatineni 2020-04-30 21:26 ` Sowjanya Komatineni 2020-04-30 21:37 ` Sowjanya Komatineni 2020-04-30 21:37 ` Sowjanya Komatineni [not found] ` <289d9c92-383f-3257-de7b-46179724285a-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-04-30 21:53 ` Sowjanya Komatineni 2020-04-30 21:53 ` Sowjanya Komatineni [not found] ` <9aa64f21-7b23-7228-b5eb-d2ff092682ad-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-04-30 22:16 ` Sowjanya Komatineni 2020-04-30 22:16 ` Sowjanya Komatineni [not found] ` <668cc4a0-2c81-0d87-b801-9fbf64e19137-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-04-30 22:19 ` Sowjanya Komatineni 2020-04-30 22:19 ` Sowjanya Komatineni [not found] ` <bf3f654e-b8f8-d560-fc5e-03d73cb7eab0-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-04-30 23:14 ` Sowjanya Komatineni 2020-04-30 23:14 ` Sowjanya Komatineni [not found] ` <fe7ebad6-0368-b1f0-4f58-648baa5e3f79@nvidia.com> [not found] ` <4f095181-2338-3b71-316c-f8bbfc7865cc@nvidia.com> [not found] ` <50e872bb-913a-7b47-3264-af6b1cedb0e2@nvidia.com> [not found] ` <e17a8a49-be53-465d-f64c-3f4c77391d98@nvidia.com> [not found] ` <da5154b4-85f9-3e56-a440-f75debaec3a8@nvidia.com> [not found] ` <cbb047ae-97dc-8b9a-a5ba-8e2a5dab3771@nvidia.com> [not found] ` <6ae2d00d-7955-d12b-5b56-955ef72ece26@nvidia.com> [not found] ` <6ae2d00d-7955-d12b-5b56-955ef72ece26-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-05-02 15:16 ` Dmitry Osipenko 2020-05-02 15:16 ` Dmitry Osipenko [not found] ` <f9073b28-f1f1-636c-be53-764fb0a531a1-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2020-05-02 15:38 ` Sowjanya Komatineni 2020-05-02 15:38 ` Sowjanya Komatineni [not found] ` <1767e50f-efb7-5e89-22f6-0917821b660d-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-05-02 16:03 ` Sowjanya Komatineni 2020-05-02 16:03 ` Sowjanya Komatineni 2020-05-02 16:14 ` Sowjanya Komatineni 2020-05-02 16:14 ` Sowjanya Komatineni 2020-05-02 16:55 ` Sowjanya Komatineni 2020-05-02 16:55 ` Sowjanya Komatineni 2020-05-02 17:04 ` Sowjanya Komatineni 2020-05-02 17:04 ` Sowjanya Komatineni [not found] ` <605fc688-7712-cdfd-9d12-5741b984bb68-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-05-02 19:14 ` Sowjanya Komatineni 2020-05-02 19:14 ` Sowjanya Komatineni 2020-05-02 20:48 ` Dmitry Osipenko [not found] ` <4abf30e0-fed9-ba39-ae38-350789bce99d-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2020-05-02 22:46 ` Sowjanya Komatineni 2020-05-02 22:46 ` Sowjanya Komatineni [not found] ` <b5f6a4e0-6e97-05ae-f034-b84fc5a1129a-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-05-03 0:03 ` Sowjanya Komatineni [this message] 2020-05-03 0:03 ` Sowjanya Komatineni 2020-05-04 12:18 ` Hans Verkuil 2020-05-04 12:18 ` Hans Verkuil 2020-05-04 14:50 ` Sowjanya Komatineni 2020-05-04 14:50 ` Sowjanya Komatineni 2020-04-30 21:22 ` Sowjanya Komatineni 2020-04-30 21:22 ` Sowjanya Komatineni [not found] ` <960d2715-a717-0cc3-df19-ff78dc426535@nvidia.com> [not found] ` <960d2715-a717-0cc3-df19-ff78dc426535-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-05-04 15:53 ` Dmitry Osipenko 2020-05-04 15:53 ` Dmitry Osipenko [not found] ` <23520fa4-4d8f-b083-0ad3-b249339ee032-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2020-05-04 15:56 ` Sowjanya Komatineni 2020-05-04 15:56 ` Sowjanya Komatineni 2020-04-30 14:25 ` Dmitry Osipenko 2020-04-30 14:25 ` Dmitry Osipenko 2020-04-30 14:26 ` Dmitry Osipenko 2020-04-30 20:06 ` Dmitry Osipenko 2020-04-30 20:08 ` Sowjanya Komatineni 2020-04-30 20:08 ` Sowjanya Komatineni [not found] ` <bfd82642-9648-96f1-737d-4b9a869d34a3-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-04-30 20:09 ` Sowjanya Komatineni 2020-04-30 20:09 ` Sowjanya Komatineni 2020-04-30 20:21 ` Dmitry Osipenko [not found] ` <8da0929d-4a58-75b8-381c-511ce66f8d9d-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2020-04-30 20:21 ` Sowjanya Komatineni 2020-04-30 20:21 ` Sowjanya Komatineni 2020-05-04 7:44 ` Dmitry Osipenko [not found] ` <f1cbb602-163e-a539-aaa5-c7e947a8945b-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> 2020-05-04 14:36 ` Sowjanya Komatineni 2020-05-04 14:36 ` Sowjanya Komatineni 2020-04-29 22:00 ` [RFC PATCH v11 7/9] MAINTAINERS: Add Tegra Video driver section Sowjanya Komatineni 2020-04-29 22:00 ` Sowjanya Komatineni [not found] ` <1588197606-32124-1-git-send-email-skomatineni-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org> 2020-04-29 22:00 ` [RFC PATCH v11 8/9] dt-bindings: reset: Add ID for Tegra210 VI reset Sowjanya Komatineni 2020-04-29 22:00 ` Sowjanya Komatineni 2020-04-29 22:00 ` [RFC PATCH v11 9/9] arm64: tegra: Add Tegra VI CSI support in device tree Sowjanya Komatineni 2020-04-29 22:00 ` Sowjanya Komatineni 2020-04-30 9:59 ` [RFC PATCH v11 0/9] Add Tegra driver for video capture Hans Verkuil [not found] ` <4c66453f-d514-8667-a326-cd01f75a17b9-qWit8jRvyhVmR6Xm/wNWPw@public.gmane.org> 2020-04-30 17:02 ` Sowjanya Komatineni 2020-04-30 17:02 ` Sowjanya Komatineni
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