From mboxrd@z Thu Jan 1 00:00:00 1970 From: Daniel Vetter Subject: Re: TIMESTAMP register Date: Tue, 17 Apr 2012 23:04:18 +0200 Message-ID: <20120417210418.GS4104@phenom.ffwll.local> References: <36D38C1F74839847A52A484C31F3E51A154A0E59@IRSMSX101.ger.corp.intel.com> <20120417193943.GR4104@phenom.ffwll.local> <36D38C1F74839847A52A484C31F3E51A154A12B9@IRSMSX101.ger.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-wg0-f43.google.com (mail-wg0-f43.google.com [74.125.82.43]) by gabe.freedesktop.org (Postfix) with ESMTP id 52D299E744 for ; Tue, 17 Apr 2012 14:03:24 -0700 (PDT) Received: by wgbdr12 with SMTP id dr12so5483048wgb.12 for ; Tue, 17 Apr 2012 14:03:23 -0700 (PDT) Content-Disposition: inline In-Reply-To: <36D38C1F74839847A52A484C31F3E51A154A12B9@IRSMSX101.ger.corp.intel.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+gcfxdi-intel-gfx=m.gmane.org@lists.freedesktop.org To: "Lawrynowicz, Jacek" Cc: "intel-gfx@lists.freedesktop.org" List-Id: intel-gfx@lists.freedesktop.org On Tue, Apr 17, 2012 at 08:34:11PM +0000, Lawrynowicz, Jacek wrote: > ARB_timer_query allows client read TIMESTAMP both asynchronously and synchronously. > The former can be implemented as you said but the latter requires support from the KMD. > This must be a simple MMIO read as this is the only way to report "current" GPU time. > Implementing synchronous TIMESTAMP query using pipe control would render the third example from ARB_timer_query spec useless. Ok, I've looked like a dofus again, but now I've read the spec and we indeed seem to need a synchronous readout of the TIMESTAMP register. I guess a new register will do, together with some fixed-point integer that tells userspace how to convert it to nanoseconds. -Daniel -- Daniel Vetter Mail: daniel@ffwll.ch Mobile: +41 (0)79 365 57 48