Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751508AbdLNJFk (ORCPT ); Thu, 14 Dec 2017 04:05:40 -0500 Received: from mail-ot0-f196.google.com ([74.125.82.196]:36200 "EHLO mail-ot0-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751027AbdLNJFf (ORCPT ); Thu, 14 Dec 2017 04:05:35 -0500 X-Google-Smtp-Source: ACJfBosYXLF3x4Uwc9Ek8TXMaN0qgvLZizu1JcTBmnC4maexYs/CBL8n59kO+YwZ12F6Ri2SJZW2iV5Q+m7QYIVpdno= MIME-Version: 1.0 In-Reply-To: <20171213205635.GB16788@promb-2n-dhcp36.eng.vmware.com> References: <20171127111629.1682286-1-arnd@arndb.de> <20171213205635.GB16788@promb-2n-dhcp36.eng.vmware.com> From: Arnd Bergmann Date: Thu, 14 Dec 2017 10:05:34 +0100 X-Google-Sender-Auth: CxbTYmPNmf4fEta4TMEv3IzrE5o Message-ID: Subject: Re: [PATCH] vmwgfx: use monotonic event timestamps To: Sinclair Yeh Cc: VMware Graphics , Thomas Hellstrom , David Airlie , Deepak Singh Rawat , Tomi Valkeinen , Arvind Yadav , Ravikant B Sharma , Joe Perches , dri-devel , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 697 Lines: 14 On Wed, Dec 13, 2017 at 9:56 PM, Sinclair Yeh wrote: > This looks okay to me. Although we should change eaction->tv_* type > to 64-bit as well. I thought about it but it would add significant complication without real gain, as the eaction->tv_* pointers point into uapi structures (drm_vmw_event_fence and drm_event_vblank) that are defined as 32-bit times and cannot be changed. Changing the temporary pointer to 64 bit would require adding a temporary variable to point to and then doing the truncation in the callers. With monotonic times, we know that 32-bit times are sufficient, they are good for 136 years after boot (68 years when interpreted as signed). Arnd