From: Esaki Tomohito <etom@igel.co.jp> To: "Enrico Weigelt, metux IT consult" <lkml@metux.net> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>, Maxime Ripard <mripard@kernel.org>, Thomas Zimmermann <tzimmermann@suse.de>, David Airlie <airlied@linux.ie>, Daniel Vetter <daniel@ffwll.ch>, Laurent Pinchart <laurent.pinchart@ideasonboard.com>, Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>, dri-devel@lists.freedesktop.org, linux-renesas-soc@vger.kernel.org, linux-kernel@vger.kernel.org, devicetree@vger.kernel.org, linux-doc@vger.kernel.org, Damian Hobson-Garcia <dhobsong@igel.co.jp>, Takanari Hayama <taki@igel.co.jp> Subject: Re: [PATH 0/4] [RFC] Support virtual DRM Date: Tue, 22 Jun 2021 13:03:39 +0900 [thread overview] Message-ID: <1cfab5f9-f275-aa53-00de-5da3fcea71c5@igel.co.jp> (raw) In-Reply-To: <7cde82a9-c60c-e527-eeac-eaad0c5842a1@metux.net> Hi, Enrico Weigelt Thank you for reply. On 2021/06/22 1:05, Enrico Weigelt, metux IT consult wrote: > On 21.06.21 08:27, Tomohito Esaki wrote: > > Hi, > >> Virtual DRM splits the overlay planes of a display controller into multiple >> virtual devices to allow each plane to be accessed by each process. >> >> This makes it possible to overlay images output from multiple processes on a >> display. For example, one process displays the camera image without compositor >> while another process overlays the UI. > > Are you attempting to create an simple in-kernel compositor ? I think the basic idea is the same as DRMlease. We want to separate the resources from the master in units of planes, so we proposed virtual DRM. I think the advantage of vDRM is that you can use general DRM APIs in userland. > I don't think that's not the way to go, at least not by touching each > single display driver, and not hardcoding the planes in DT. Thank you for comment. I will reconsider about DT. > What's the actual use case you're doing that for ? Why not using some > userland compositor ? I think when latency is important (e.g., AR, VR, for displaying camera images in IVI systems), there may be use cases where the compositor cannot be used. Normally, when the image is passed through the compositor, it is displayed after 2 VSYNC at most, because the compositor combines the image with VSYNC synchronization. On the other hand, if we use vDRM, the image will be displayed at the next VSYNC, so it will be displayed after 1 VSYNC at most. Also, since the compositor is a single point of failure, we may not want to make it dependent on it. Best regards Tomohito Esaki
WARNING: multiple messages have this Message-ID (diff)
From: Esaki Tomohito <etom@igel.co.jp> To: "Enrico Weigelt, metux IT consult" <lkml@metux.net> Cc: devicetree@vger.kernel.org, Takanari Hayama <taki@igel.co.jp>, Thomas Zimmermann <tzimmermann@suse.de>, linux-doc@vger.kernel.org, David Airlie <airlied@linux.ie>, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-renesas-soc@vger.kernel.org, Kieran Bingham <kieran.bingham+renesas@ideasonboard.com>, Laurent Pinchart <laurent.pinchart@ideasonboard.com>, Damian Hobson-Garcia <dhobsong@igel.co.jp> Subject: Re: [PATH 0/4] [RFC] Support virtual DRM Date: Tue, 22 Jun 2021 13:03:39 +0900 [thread overview] Message-ID: <1cfab5f9-f275-aa53-00de-5da3fcea71c5@igel.co.jp> (raw) In-Reply-To: <7cde82a9-c60c-e527-eeac-eaad0c5842a1@metux.net> Hi, Enrico Weigelt Thank you for reply. On 2021/06/22 1:05, Enrico Weigelt, metux IT consult wrote: > On 21.06.21 08:27, Tomohito Esaki wrote: > > Hi, > >> Virtual DRM splits the overlay planes of a display controller into multiple >> virtual devices to allow each plane to be accessed by each process. >> >> This makes it possible to overlay images output from multiple processes on a >> display. For example, one process displays the camera image without compositor >> while another process overlays the UI. > > Are you attempting to create an simple in-kernel compositor ? I think the basic idea is the same as DRMlease. We want to separate the resources from the master in units of planes, so we proposed virtual DRM. I think the advantage of vDRM is that you can use general DRM APIs in userland. > I don't think that's not the way to go, at least not by touching each > single display driver, and not hardcoding the planes in DT. Thank you for comment. I will reconsider about DT. > What's the actual use case you're doing that for ? Why not using some > userland compositor ? I think when latency is important (e.g., AR, VR, for displaying camera images in IVI systems), there may be use cases where the compositor cannot be used. Normally, when the image is passed through the compositor, it is displayed after 2 VSYNC at most, because the compositor combines the image with VSYNC synchronization. On the other hand, if we use vDRM, the image will be displayed at the next VSYNC, so it will be displayed after 1 VSYNC at most. Also, since the compositor is a single point of failure, we may not want to make it dependent on it. Best regards Tomohito Esaki
next prev parent reply other threads:[~2021-06-22 4:03 UTC|newest] Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-06-21 6:27 [PATH 0/4] [RFC] Support virtual DRM Tomohito Esaki 2021-06-21 6:27 ` [PATH 1/4] drm: Add Virtual DRM device driver Tomohito Esaki 2021-06-21 6:27 ` [PATH 2/4] rcar-du: Add support virtual DRM device Tomohito Esaki 2021-06-21 6:27 ` [PATH 3/4] dt-bindings: display: Add virtual DRM Tomohito Esaki 2021-06-21 6:27 ` [PATH 4/4] doc-rst: Add virtual DRM documentation Tomohito Esaki 2021-06-21 7:10 ` [PATH 0/4] [RFC] Support virtual DRM Thomas Zimmermann 2021-06-21 9:24 ` Maxime Ripard 2021-06-22 4:36 ` Esaki Tomohito 2021-06-22 4:36 ` Esaki Tomohito 2021-06-23 14:39 ` Maxime Ripard 2021-06-23 14:39 ` Maxime Ripard 2021-06-22 4:02 ` Esaki Tomohito 2021-06-22 4:02 ` Esaki Tomohito 2021-06-22 7:57 ` Pekka Paalanen 2021-06-22 7:57 ` Pekka Paalanen 2021-06-23 8:04 ` Michel Dänzer 2021-06-23 8:21 ` Esaki Tomohito 2021-06-22 9:12 ` Thomas Zimmermann 2021-06-22 9:12 ` Thomas Zimmermann 2021-06-21 16:05 ` Enrico Weigelt, metux IT consult 2021-06-22 4:03 ` Esaki Tomohito [this message] 2021-06-22 4:03 ` Esaki Tomohito 2021-06-22 8:12 ` Pekka Paalanen 2021-06-22 8:12 ` Pekka Paalanen 2021-06-22 19:12 ` Daniel Vetter 2021-06-22 19:12 ` Daniel Vetter 2021-06-23 6:56 ` Esaki Tomohito 2021-06-23 6:56 ` Esaki Tomohito 2021-06-23 8:39 ` Pekka Paalanen 2021-06-23 8:39 ` Pekka Paalanen 2021-06-23 9:22 ` Esaki Tomohito 2021-06-23 9:22 ` Esaki Tomohito 2021-06-23 11:41 ` Pekka Paalanen 2021-06-23 11:41 ` Pekka Paalanen 2021-06-25 1:55 ` Esaki Tomohito 2021-06-25 1:55 ` Esaki Tomohito 2021-06-21 6:43 Tomohito Esaki 2021-06-21 6:43 ` Tomohito Esaki 2021-06-22 8:04 ` Simon Ser 2021-06-22 8:04 ` Simon Ser
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