Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753251AbdGFHp2 (ORCPT ); Thu, 6 Jul 2017 03:45:28 -0400 Received: from mail.netline.ch ([148.251.143.178]:51299 "EHLO netline-mail3.netline.ch" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752762AbdGFHp0 (ORCPT ); Thu, 6 Jul 2017 03:45:26 -0400 Subject: Re: [PATCH 1/3] drm: Widen vblank count to 64 bits. Change vblank time precision to ns To: Keith Packard , Dave Airlie , Daniel Vetter Cc: linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org References: <20170705221013.27940-1-keithp@keithp.com> <20170705221013.27940-2-keithp@keithp.com> From: =?UTF-8?Q?Michel_D=c3=a4nzer?= Message-ID: <83a2dbe9-dfcb-e31e-fc7b-14c4364daea5@daenzer.net> Date: Thu, 6 Jul 2017 16:45:10 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.0 MIME-Version: 1.0 In-Reply-To: <20170705221013.27940-2-keithp@keithp.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-CA Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1512 Lines: 41 On 06/07/17 07:10 AM, Keith Packard wrote: > This modifies the datatypes used by the vblank code to provide both 64 > bits of vblank count and to increase the resolution of the vblank > timestamp from microseconds to nanoseconds. > > The driver interfaces have also been changed to return 64-bits of > vblank count; fortunately all of the code necessary to widen that value > was already included to handle devices returning fewer than 32-bits. > > This will provide the necessary datatypes for the Vulkan API. > > Signed-off-by: Keith Packard [...] > @@ -1492,9 +1515,11 @@ int drm_wait_vblank(struct drm_device *dev, void *data, > > switch (vblwait->request.type & _DRM_VBLANK_TYPES_MASK) { > case _DRM_VBLANK_RELATIVE: > - vblwait->request.sequence += seq; > + req_seq = seq + vblwait->request.sequence; > vblwait->request.type &= ~_DRM_VBLANK_RELATIVE; Subtle breakage here: vblwait->request.sequence must still get updated for _DRM_VBLANK_RELATIVE, in case we're interrupted by a signal. > @@ -317,6 +317,9 @@ int via_driver_irq_postinstall(struct drm_device *dev) > if (!dev_priv) > return -EINVAL; > > + if (dev->driver->get_vblank_counter) > + dev->max_vblank_count = 0xffffffff; What's the purpose of this? All drivers providing get_vblank_counter should already initialize max_vblank_count correctly. -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer