From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.kernel.org ([198.145.29.136]:54236 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751774AbdCAOIr (ORCPT ); Wed, 1 Mar 2017 09:08:47 -0500 From: Kieran Bingham To: laurent.pinchart@ideasonboard.com, linux-renesas-soc@vger.kernel.org Cc: linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, Kieran Bingham Subject: [RFC PATCH 0/3] RCAR-DU, VSP1: Prevent pre-emptive frame flips on VSP1-DRM pipelines Date: Wed, 1 Mar 2017 13:12:53 +0000 Message-Id: Sender: linux-media-owner@vger.kernel.org List-ID: The RCAR-DU utilises a running VSPD pipeline to perform processing for the display pipeline. Changes to this pipeline are performed with an atomic flush operation which updates the state in the VSPD. Due to the way the running pipeline is operated, any flush operation has an implicit latency of one frame interval. This comes about as the display list is committed, but not updated until the next VSP1 interrupt. At this point the frame is being processed, but is not complete until the following VSP1 frame end interrupt. To prevent reporting page flips early, we must track this timing through the VSP1, and only allow the rcar-du object to report the page-flip completion event after the VSP1 has processed. [PATCH 1/3] fixes the VSP DRM object to register it's pipeline correctly. [PATCH 2/3] extends the VSP1 to allow a callback to be registered allowing the VSP1 to notify completion events, and extend the existing atomic flush API to allow private event data to be passed through. [PATCH 3/3] Utilises this API extension to postpone page flips as required. In current testing, with kmstest, and kmscube, it can be seen that our refresh rate has halved. I believe this is due to the one frame latency imposed by the VSPD and will need further investigation. Kieran Bingham (3): v4l: vsp1: Register pipe with output WPF v4l: vsp1: extend VSP1 module API to allow DRM callback registration drm: rcar-du: Register a completion callback with VSP1 drivers/gpu/drm/rcar-du/rcar_du_crtc.c | 8 ++++- drivers/gpu/drm/rcar-du/rcar_du_crtc.h | 1 +- drivers/gpu/drm/rcar-du/rcar_du_vsp.c | 34 ++++++++++++++++++++- drivers/media/platform/vsp1/vsp1_drm.c | 43 +++++++++++++++++++++++++-- drivers/media/platform/vsp1/vsp1_drm.h | 12 ++++++++- include/media/vsp1.h | 6 +++- 6 files changed, 99 insertions(+), 5 deletions(-) base-commit: a194138cd82dff52d4c39895fd89dc6f26eafc97 -- git-series 0.9.1